Unbroke & G.L:
The '54 engine mostly "drops-in", however the bell housing is different: '47-'53 has the u-shaped mounts that sit on "horizontal" portions of the cross-member, '54 & later has the "biscuit-type" mounts that sit on the angled cross-member.
What you'll need to do (hope you read this before you try and drop that '54 engine in there!) is swap the bell housing from your '50 engine onto the '54 engine; then she'll fit just fine.
To change bell-housings you'll need to remove the clutch and the flywheel, then you'll see the bolts that hold the bell housing to the block.
Good luck!
A good Tech Tip
