340 seems to be locked up

STOP NOW. Most likely you don't have the converter all they way into the pump. Stop turning it as at this point you can damage the thrust main enough that it won't fail on fire up but 5000 miles from now the thrust will be shot.

You can tell when the converter is all the way into the pump. Number one is the converter should be so far into the tranny that it looks like it will hit the case. Number two is you should have to pull the converter at least a 1/2 inch before it meets up with the flex plate.

If those two thing didn't happen stop and make it happen.