I'll close this discussion for now. I'm doing a complete about-face and dropped a good chunk of my budget on the RC-107 kit. I'm going to rehab (fix oil leaks, etc.) my 306 while I have it out and then plop it back in. In addition to the RC-107 I'm going to focus on exhaust, gears, and transmission while keeping a slow eye out for a 351.
You're better off with a 302 based stroker in these cars. Whole lot less headache trying to fit them vs a 351
