Ooh, ohh, I know the answer to this one!
I will add a few tidbits, and please feel free to ask anything else:
Don't get to hung up on the "late suspension is better" thing. I have both, (64 mostly stock Convertible and 65 coupe modified car). With modern tires and in good condition you will not notice much difference unless you are doing performance driving. Even in that case the earlies can be made safe and reasonable handling cars (see pic above), they are just a bit more limited (swing axle defines camber). The real reason to choose between the two is what styling you like (I prefer the styling of the early convertibles, and the late coupes)
Probably the biggest "issue" with the cars is that the drivetrain is VERY different from Amercian cars of the time (BTW suspension parts in general is very similar to US cars of the time). Because of this difference, many people have no idea where to even start with them, but there are plenty of people out there who do. Because of the difference there is also very few new parts for major components (e.g. no new heads, block or cranks).
Because of this, full engine rebuild are relatively pricey (heck even aircoooled VW's are a bit pricey these days). A quality rebuilt can push over $3000 easy. Cheaper ones can be done of course (depending on condition etc.)
As with any 60's GM car (as noted): RUST RUST RUST. Earlies are actually a little better with rust in a way. They will rust the floors and trunk bottom of course. The primary area to look are the rockers, specifically the drain in front of the front door, the area from the doors back, and the rear area (splash from tire). Doors also have some very nice places to capture crap an the front and rear bottom.
The water drain for the rear windows is silly to say the least. I am just finishing up doing a bunch of (California) rust repair on my 64, so I am very familiar with the goofiness. If you are interested, I can post some pictures of the issues on my car so you can see what I am talking about.
Good cars can be found pretty cheap. Buying a really cheap poor condition car is almost never going to be worth it unless you are a masochists.
One important note about "restored" cars. Corvairs have been cheap for a LONG time. In general, there has been little reason to put money into a restoration, because of that be VERY careful with cars that have been repainted or "restored". There is not shortage of Bondo bucket Earl Shive special Corvairs out there. Original pain, even very poor paint, in general is highly preferred.
