Hello and welcome.... just so you don't think you're going mad, I have deleted your other post which was a near duplicate of this one, but wouldn't have shown up as it hadn't been approved (all first posts need approval before being viewable to try and stop spam).
Anyway, there are no 'quick and simple' answers to your question..... and even no single correct answer. Lets start with what should be the "simple" things.... oil and spark plugs.
I recently fitted a set of Denso iridium sparkplugs to my project car -
part number 5304 - I didn't pay that, because I got them from Rockauto for a fiver each..... there are a set on Ebay for £18, which looks great, except the advert doesn't fill me with confidence as it says they can be collected from Leeds, but will take 7-10 days for postage from Hong Kong..... either way, they are a great plug that will last the lifetime of the car. If you don't want them to be "that good" there are plenty of cross referenced items for a few quid less, however, they are not really considered to be a 'service item' and are replaced when required more than at a set time/distance (but as an unknown quantity on an unknown car, it makes sense to do them - that's what I did!).
Okay, so on to oil

Everyone asks the question, and everyone then gets 99 different answers - none of them are wrong!!!!
The book says to use whatever was about 30+ years ago, oil companies will tell you to use whatever they think the average Elan will need 30+ years later, and the truth is somewhere in the middle. Basically, it all depends on the state of your engine NOW, not what it was like when it left the factory. If it has been maintained with regular oil changes and not run ridiculously hot, then I would suggest using a standard 5w30 synthetic on anything under 100K miles, but going slightly thicker if over that figure (10w40). I have 10w60 in my car but it is a little too thick really, so I dilute it with a thinner oil to get a blend resulting in 7.5w50. Of course, this is all guesswork until you fire up the engine, so in your case I'd suggest a gallon of 5w30 or 10w40 (even going semi-synthetic) and see how it runs - then chose another viscosity based on how it works for you, and change it in a few months time (or use). Any clean oil now will be better than the "right" oil 2 years ago. I chucked a gallon of cheap
10w40 Mannol oil in mine to get it going, and it was nearly a year ago (but no real use), so will be changed for a decent fully synthetic oil this year. It works fine!
For the engine, I always use Rockauto for parts which are 'service' items..... ordering from them is easy and quick (delivery). Bear in mind that they have multiple warehouses, and not everything ships from the same location...... so there may be a choice of 4 water pumps, but the cheapest one may have a separate delivery charge to the cam belt, so it may be cheaper overall to get a more expensive water pump from the same warehouse so it all arrives in one box.
I'm sure that your next question may be "is there a standard shopping list?" - and the answer is no! - basically, their inventory changes frequently, so what is listed today may or may not be available in 3 months time - but they may have something else. There are a whole host of things they sell which fit the elan (rear brakes/pads are from an Oldsmobile Cutlass Supreme), and also a lot of stuff they list for the Isuzu Impulse Turbo which is the same as used in the Elan....but not everything is the same (like alternator belts).
In your case, I appreciate that changing the cambelt is an obvious first thought, but if the car's history is unknown, then I would also change the tensioner and idler whilst I'm there (and, obviously, the water pump).... whilst the pulleys are not a 'service item' they will wear with age and use. My philosophy is to change them with the first belt I fit on an unknow car, then after that, just do the belt & pump every 5-6 years.
Having a quick look at todays offerings from Rocks, I tried adding and subtracting various combinations of items, and ended up with the following "best value" shopping list....... note, it is possible to add a set of rear brake pads for a tenner, but it increases the total by £25 due to the heavier parcel for shipping! - still a bargain if you want some, as they are cheap as chips in USA, but only 3 makes were ever submitted for EU "E" marking, so they can't be sold in the UK for road use (but are legal to buy from outside the UK, and fit to a UK car!).
Things like ignition coils are a tenner each, an alternator is about £61, a clutch kit is £138 (for the right one - make sure it is 8 7/8" diameter, as some are smaller, but will still fit the Elan.... won't last as long though)........ so it can save a huge chunk of cash by buying from a 'different' supplier than from a "UK Lotus Specialist". (and you'll probably get the exact same items in your parcel).
cambelt cart.png
cam belt shipping.png
Always remember to choose a 'shipping option' which includes the VAT and any duty payments included, otherwise (if you get caught for it) it will delay your parcel at East Midlands airport until you pay the fees via Royal Mail, who will also add on a £12 "Admin Charge"......
.... there is usually a 5% discount code online which you add in the "Where did you hear about us" box.....
.....and although you can pay with PayPal (and lots of other options), it is worth using a credit/debit card which doesn't charge a foreign transaction fee and make the payment in dollars. I use a Starling Debit Account (free to set up and very easy to use in UK and abroad), and it would save $6 using their exchange rates rather than PayPals today.
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