[rotorwrench]

The late 51 Merc bell housing is an excellent candidate for addapting any of the Borg Warner narrow 4-bolt transmissions to the 8BA family of flathead V8s. If you can find one of the offset rocker set ups for the solenoid that the convertible cars used, it would likely get the thing out of the way of the frame members. I've seen a fellow fabricate one of these or similar contraption over on the HAMB. There is an illustration of one in the 49 to 53 Ford car chassis parts catalog. It relocates the solenoid down underneath the tail shaft housing and push & pull activates the overdrive through a rocker arm much like an OHV engine works the valves.

You can braze it up but that transmission was relatively popular in the early 50s. You should be able to find one somewhere. Joblot in NY or Stacy Brown at Antique Auto Supply in Arlington, TX may have NOS parts for them. The 52 & 53 cars still aren't as popular as the smaller shoe box cars are. Flat Top Bob at Owen's Salvage Co in Wellington, TX has a salvage yard with a lot of cars that go back into that era.