[bobH]

59A crank uses full-floating rod bearings, as (most) all 32-48's have. Bearings cost more, and some 'talent' is required to properly fit them (so they will 'float'). 8BA crank uses rods with 'locked' bearing inserts, which has been the common 'industry-standard' from 1949 forward (regardless of make). Insert bearings cost less, and are generally easier to install, requiring less talent (assuming the machinist does a proper job). A few 59A engines came originally equipped with 8BA rods and crank, as well as 8BA valve assemblies. (My 47 has one of these 59A engines - probably a 59A replacement engine.)
Your engine is partway there, as you indicated in post 167 that you probably have 8BA valve assemblies.
It would be logical, at least to me, to add the 8BA rods and crank, or maybe a Merc crank if you want a few more inches.
All this info is available in old posts, and I believe, in Ron's book.
The info i've posted here, pretty much goes out the window, if you select a stroke larger than 4.0 (Merc). I think larger strokes require floating rod bearings.