have you checked cranking compression?
have you run a leakdown test?
I would also pull the timing cover and check the cam timing with a degree wheel and know where the cam is especially if cranking compression is low, I don't trust dot to dot on cam timing.
also what stall is the converter and rear gear ratio? and does it pull the motor down and want to die when you put it in gear, if so it probably need's a little more converter as long as the tune is good, just some things that come to mind.