Sounds like a bad pinion bearing.
2" inch exhaust?
Who put that on?
If it was a shop that uses a shoe bender the curves are way less than 2" cross section. Check Jeg, Summit, TTI and others for a decent mandrel bent system. Go for 2.5" unless you want to terrify the ricers, then look at the 3" systems out there.
Having had a 350 hp New Yorker 440 in a 1964 Savoy and a 365 hp in a 1968 GTX I can say there is a world of difference between the two as far as power output goes.