Matt, can't help with the aluminum tappet blocks, but my '48 (early) had iron blocks, the duplicate of the aluminum ones. Definitely not '53 versions. Ever seen a set?
If I can find some in my Dad's stash you know they will have a new home in S.D.!!!!
Matt, I've got a set but they need work. Seeing what you can do with cases & motormounts I don't see a big problem. I'll e-mail some pix. Merry Christmas ! Rick