[garyd1961]

I don't care what your mechanic says, it sounds like a timing issue. You stated it wouldn't turn over when hot but you disconnected the distributor and it turned over fine, that says the timing is too high.
This is how we use to set our timing in the old days. Get the motor good and hot and keep turning the timing up until it cranks slow then back it up until it cranked like it should and leave it. "Warning" this doesn't work so good on modern motors with vortec heads.