You are trying to run too much cam for the stock gearing. I would bet a 79 vette has a 2.73 or a 3.08 gear.
I would run no more than a compcam 260H cam with your stall and gear and compression. Plus the 260H is less likely to go flat due to slower ramps.
pull the engine and completely disassemble and clean it. I bet at least one of the engine bearings are chewed up after your cam when flat.
use an oil additive. www.zddplus.com