Well I once had a 33 Ford with a 365 Cad adapted to the closed drivetrain. There are adapters, but you might have to do some looking for a flywheel for it. Flywheels can also be adapted if needed.
Yes, aluminum adapters and flywheels existed back in the day. No, they're not easily found today and they're not cheap. Maybe, depends upon your friends and contacts. It's just time and money. Also, are you flexible about your*******? Cad-to-whatever are specific and if you find one, are you willing to live with that******* and make it fit your frame and driveline? The best one to find would be a Cad-to-Studebaker or others which used the Borg-Warner bolt pattern. Then, you could use a T85 or T10. Just be aware the B-W transmissions used application-specific input shafts. The depth of a Stude adapter will be different than a Ford adapter. jack vines
Just curious...are there any common bolts or dowels from the early Cad to the BOP? Could be a starting point....
I seem to remember a customer, when I worked in a filling station, who had a 62 or 63 Cadillac with a 3 speed on the column. It was supposed to be a special order. I know the sales data books back in the 60's had all kinds of off the wall options.
I bought a Speed Gems kit, but I haven't bolted it up yet. Not cheap, but it will let you bolt up any Chevvie bolt pattern manual. CA102 1954 and up Cadillac 365/390 to Chevy Manual — Speed Gems (transmissionadapters.com) They even have a video. Speed Gems 55-64 Early Cadillac to Chevy Automatic and Manual Transmission Adapter Installation - YouTube -Abone.