Truck pumps ('37-47 type) have close together dual sheaves and are LONGER than passenger '37-48, which are what you want. You got garbled info referring to '49-up engine adapting. be thankful you have the early, as 8BA types are significantly longer unles cam and all front stuff is swapped for early.
Somewhere on the HAMB I posted dimensions, but your basic needs are passenger pumps, crab, and fan mount generator. Easiest to find crank pulley is simply any '40-48 with front sheave trimmed away.