Initial timing

Was it a fresh build engine that sat for 4 years? Or an existing running engine that sat for 4 years.

Either way unless you re-primed that oil system that cam was going to be running dry. Burning the peaks off the lobes and digging into the lifters.

Especially true if you have higher than stock valve spring pressures.

Especially true if you have a higher lift cam than factory stock.

Please tell me it's a stock 273.