I've nothing to add but good luck (never even owned a auto)
Oldtimers, Youngtimers and Vintage Motoring
A community for everything old and youngtimers! That includes Cars, Bikes, Trucks, Bicycles and all other old Personal Vehicles!
Oldtimers are Defined as Vehicles 30 years or older, whereas Youngtimers are between 25 and 30 years of age!
Research - you really need to verify why things are different, what those "bits" are. May be nothing, but you want to know.
I'm surprised to hear a failing trans kills a TC - those are simple, robust devices. Only time I've seen one damaged is in racing where they drive a lot of torque through one, very abruptly, during launch (drag racing). I don't think an SVX has the torque to bend vanes in a TC. Wonder if there's something else in these (maybe the lockup mechanism gets damaged?).
I've even overheated one, causing the case to change colors, and it worked fine later.
As for what fits (or doesn't), I'd want to rely on good research and docs, so I know how and why things fit together. It may be more than just "will it fit".