38 is a split year, early units had a 2.398 main. the later ones 2.498 the 8ba ccrank will have to be ground down to the smaller size and clearanced for the block. Thin is how the Merc crank is installed in the 36lB, and 37 blocks. I've done several.
Gramps
PS Forgot to ask if this was a 21 or 24 stud block, that ight make a difference. I also bored the block to 3 3/16
G