I have a 1972 chevelle SS original stock 402 big block with the following upgrades: headers and magnaflow exhaust, dual plane manifold, upgraded 4 barrel carb, and accel HEI distributor. My mechanic is a having a problem regarding timing. In order to get the motor running correctly he has the total advance set between 65-70 and idle at 30-35. This seems to work well with no pinging or after running. Any ideas or suggestions I can pass on to him?

It sounds like either the timing tab is off or the balancer ring has slipped.

That's the first thing I would check.

Have already tried both suggestions. Any other ideas?

Disconnect vac advance and recheck.

did you check the curve on the distributor?