I did one of these babies 20 years ago when parts were hard to find but still around. Before you start, make sure the rear axel stabiliser bar attachments to the body under the back seat have not yet rotted through. If they have, forget about any quick fix resto as it would seriously indicate if not terminal rot, a major piece of chassis engineering ahead. This is because if the hangers are to be removed, they will need to be acuratly re-positioned or else the rear end will 'crab' and handling will be attrocious! As this area is sprayed with muck, salt and was orignally poorly undersealed, its a prime indicator as to the health of the car. The engine too is an area that could be costly due to the fact its a 125 lump (becoming scarcer) not the 124/131/132 block (still common in comparison) again, the expensive bits are the gaskets, unique to the 125 (bore spacing) and the carbs (IDF's) which are a pig to restore and set up properly. The B posts would have probably gone too? These are repairable; like the suspension, there will be loads of 'putting on, aligning squaring up and taking off, cutting and grinding etc'.
The BC's are in my opinion, the best looking and sounding of all the 124 range inc. spyders! so in worth the hassle doing one up but don't get sucked into a spiral of costs, time and 'chasing repairs around the car!
Let me know how its going or if you need to ask any questions?
