340 build No POWER need help w tune

So did you go out and buy/borrow a NON-adjustable timing light yet? If your engine is as built up as you say it should have a damper with timing advance marks built in going up to at least 50* BTDC so a dial-back timing gun is pointless. If you don't have a marked damper you can do it yourself with a dremel tool and cutoff wheel; just rotate the crank 10* at a time and cut a small groove just enough to be visible. I've found this to work better and be more permanent than timing tape which can fly off.

Did reversing those distributor wires make any difference?