904 trans

Been looking for 904 cores for a small block drag car. Cant find any locally most people dont want to ship. My question is are the late 60s trans good, what upgrades do they need. I see mostly 1968 to early 70s if i find them. I have lots of 727s but having a hard time finding 904s.
I think I have a 904 I got for free when i bought my car, let me see. not sure if it is for a small block though.