Purely out of interest I 'dismantled' the old release bearing... and found it was still neatly packed full of longlife grease
We've got the gearbox mated up to the engine now, it didnt go quietly - though we found the 'bricks' trick worked the best. Gradually jack the box up higher, and prop bricks up under it slowly - this means that when it's close to the engine it's trapped in the trans tunnel and cant drop out because of the bricks! You can quite easily move it around to get it to mate properly then.
Centralising the 540 clutch is an utter ***** of a job - the release springs are so wide you cant physically fit a centraliser in there. Discovered the best way to do it is to use an 8mm hex drive bit plugged into a 1/2" to 1/4" convertor with a bit of tape wrapped around it - the 8mm hex drive bit is usually neatly flanged and centralises in the front bearing.
On the old primative Ami cars the clutch was in a seperate housing from the transmission case. Probably because everything was made of cast iron.
Aligning the clutch plate was a matter of getting it close to centered and having a helper depress the clutch pedal to free the disc while shoving it in.
I can't imagine what a hemi box with an attatched bell housing would have weighed.
"The gas pedal wouldn't go to the floor if it weren't meant to be there"