Probably the easiest option is to go with 2 derale remote coolers imo, which is what i did for my 48 swap. I made a little bracket to bolt them under my bed, and have a switch to flip the fans on.
Now i can say with this setup there are a few things that need fixed. First is they work borderline too well with converter locked on the highway. Any weather sub 50* the trans will run sub 100* pan temps. second is that it seems to take a real long time to warm up, so I think some sort of temp switch valve like factory uses may be a good idea. Final thing is i want to have the fans turn on automatically when pan temps hit a certain point, because well....im lazy. Hope this helped!