Chris
I have recently acquired a 2600 spider that sounds a bit like yours, i.e. needing restoration. I look at it like this; When I'm done (years from now) I'll know a lot about coach work on this type of hand built car, plus the engine/mechanical knowledge I'll need to acquire. I've rebuilt plenty of British sports cars MG TR etc. but for those if you need a part you can just go buy it and it will fit with minimum work. This Alfa is a whole new dimension.
When it is finished I'll have something that is a wee bit different from everyone else, in my mind a good thing.
I'm sure part location will be a problem but as I lurk around here (the BB) I keep finding sources of parts and as more of these cars are restored that sort of creates a demand which means some companies might make other parts available as there is an increased global market. If the car is broken for spares (parted out?) then its gone for good albeit helping others to keep their cars on the road.
Go on rebuild it, we can start a thread for mentally and financially broken men who have tried to restore a 2600 Spider!!!
The photo shows the side of my car (from rear lookin forward) as acquired no outer sill (rocker) rear and front wings cut away door bottoms rusted out and completely dismantled. Never buy a car like this! Problem is I've no idea what it should be like as this is how I acquired the car!! Anyway thanks to the BB I've had the chance to go and see similar vehicles in a state of rebuild to get all the data(photos, measurements, approximate measurements these were hand made and differ a lot apparantly)
Good luck
Regards
Bryan