Whilst I prefer this forum to P'heads nowadays, I would have to say ask on P'heads as 10-15 years ago there were still a lot of the guys tracking these and using them. I'd be amazed if someone didn't know the car if it is a uk car or has been here for a long time.
Failing that there'll be a Porsche club register with registrar for that model.
I don't do the club thing though so know nothing about who to contact.
Congrats to your friend though. Lucky beggar! I love 964s and the RS is pure porn. :thumb:
PS For parts your main dealer will be best for new genuine stuff. For any rare used parts try Jasmine, RPM, 9M, etc.