early 283's as original in 55 2nd had mounts off the front of the block that sat on pegs to the front OEM crossmember
to put a later sbc [350] in yer 55 you have to use an aftermarket front cross member to use the side mounts on the 350 - tranny will hang off the bellhousing same as the 6 does, or same as the 283 would
to position the new cross member, measure things up, and/or put the mount on the engine and put the whole thing in place so the bellhousing mounts sit on the stock cross member to position the new forward one
Bill
