I own a 67 Sprint that I love. The Sprints would be the best handling stock cars from Pontiac because they came with the 400 suspension in a much lighter car. However, you can easily make any stock car handle better than these were in the day with some slight improvements. The base OHCs are probably a coin flip with the other v8 FGFs.

Parts are available but you have to be patient and use the boards, EBay, etc. As far as gas mileage I have never checked. I suspect is better than a v8, but don't know for sure.

The biggest draw you will see is when you go to a show, cruise night, etc, you will have a better chance of being struck by lightning than seeing another cammer. I routinely have people saying, wow is that stock, I have never seen that before, etc, etc.

You really should go over to the OHC board and try to meet up with Sprint6. He is from VB and extremely knowledgeable. I think he owns a Tempest Sprint, but you will be able to discuss in person.