The T5 or TK trans is not you only option, as a matter of fact, you need to be aware of the gear spreads and ratio for T5s, as some are geared so low, that 1st is useless, with certain differential gear ratio choices.
Or get the parts for your trans, not much to these for rebuild.
Possibly a donor trans may be out there too.
The Chrysler A833 overdrive, 1975-86 in everything from Volares/Aspens, vans and trucks. Easy to install, with a simple adapter plate, again with other modern trans, an ebrake has to be upgraded to the rear brakes, via a diff swap.
All depends on what you want and for your intended use.
There are options, besides a T5 conversion.
Whichever route you choose, be aware of the gear spread and all of what is needed to make it work.....Good Luck$
Try this trans supplier, for parts and info, https://www.novak-adapt.com/knowledge/transmissions/manual