Hi Lee, I'd follow Jeroen's advice for sure! Also, some other lessons learned from having my e21 sprayed twice is to ideally strip everything out - carpets, sound deadening etc. This way you'll get the true picture and it will be easier to repair at this stage then discovering you have holes and corrosion MOT time and having patches welded in on as needed basis.
I'd also pay special attention to the windscreen surround. If there is any rust, replace and treat ideally because this again will be a pain if it returns and will mean taking the windscreen out.
In terms of spare parts, the situation as we all know is getting more and more difficult by the day and us E21 (and especially us E3 owners!) have to really search or be creative.
Despite not having the best experiences with Walloth Nesch, they do have a good stash and it inevitably means returning to them for parts, even if it should be a last resort at times.
I was told about this site by an E3 owner
http://www.bts-autoteile.de/ and I've ordered parts from there. All were BMW OEM and fairly priced if you'd like to see how you get on with seals for an E21.
