I dunno what went wrong with the installation, 'cause I wasn't there. BUT, it sounds like the TC wasn't fully seated in the front pump gears and now everything is in a bind causing the lockup situation.
the TC would have spun like you said without actually seating into the pump gears. then forcing it all together by tightening the bellhousing bolts has caused the problem that you described.
I know it's a lot of work, but put the jack back under the tranny and loosen ALL the bellhousing bolts. don't remove them, just back them almost out and see if things loosen up. (pry the tranny away from the motor)
if things turn, you may be able to spin the converter into the pump gears and all will be well...................but I've seen front pump gears broken by similar situations.
keep us posted.......................jjf