Have you confirmed that the heater matrix can't be repaired?
The US Spec heater assembly is A100P0103F which is a LHD, 6 Position Control. They distinguish LHD from RHD and 4 Position from 6 Position. The drive side is easy to know. The "Position" refers to the control knob in the facia (dash) that controls the air flow to the cockpit, not the number of speeds for the fan. The US (FED) car is a 6 Position model.
Further down this thread there are pictures of the two controls:
viewtopic.php?f=3&t=16183&p=256541#p219730That being said, Geoff has been keeping the heater assemblies for a while and he put several in my shipment that is still stalled in the UK.
He will join in sometime soon and tell you if he still has any left in his inventory and what it will cost including shipping. They are big and heavy, so you might be surprised at the total price.
If he doesn't have any left, you can let me know and I will see if I can get my friend in the UK to dig one out and ship it to you. We had hoped the container would have been here already and I could dispatch the remaining few from the US to help with the high shipping costs.
If you have any other questions, PLEASE use the email link to contact me directly.