The bellhousing to engine bolts are smaller than the transmission to bellhousing bolts.
I'm sure the head bolts and tranny bolts are the same because I used a pair as guide pins last time I installed a SM420, into my 1950 bellhousing that was installed on a 216.
The transmission and bellhousing are fairly easy to remove but you have to take the flywheel off to get the bellhousing off. The transmission is a 4 bolt affair and shouldn't be hard. You have to keep the flywheel from turning and take off the pressure plate bolts and flywheel bolts, which can be a pain. I use a pair of vise grips to cinch an old V-belt around the harmonic balancer and attach the free end to something strong, like the generator bracket.
