1970 Monte Carlo 496 problem

I currently have a problem with a 496 engine that I have been unable to track down. The engine acts like it is dropping cylinders or is on a rev limiter mostly around 2500-3000 RPM when loaded. This started after a roller lifter went bad and damaged a lobe on the Camshaft. The engine was completely gone through and the Camshaft was sent back for repairs, it has never been right since. I have ran through the valves, changed out the Carb, complete ignition system, plugs (numerous times), and swapped intake manifolds with no fix. Once the motor has reached operating temperature and then shut off for any where from 30 minutes to 1 hour the symptoms seem to lessen significantly. Right now I am at a complete loss of where to check next. Any ideas? I am thinking maybe the Camshaft was not repaired correctly and could be causing the problems since this is where the problems seem to originate from.

I am moving this to Chevrolet classics, I think it will get more att'n there.