"Hydraulic Bellhousing"??? The clutch arm and then the slave can't be just moved to another older type housing and bolt on using same pivot and some hole allready there? B/house all diff? Can't Imagine GM would make all new for a couple of years before the change to 230 engines in 63!
Is this engine out of truck? Must be super pain in not! I removed the little ispecton cover at top of housing and used a long estension and swivel sockets, not the u-joint and socket, the one-pc sockets that swivel are shorter. You can also go thru the slot some from the throw-out arm. Smaller clutch would be helpful for sure.