id suggest getting away from the older shorter transmissions all together and go with a w56. iv always had good luck with 20r carbs there real simple and easy to work on. when i run a toy carb i prefer to keep/fix the emissions stuff so the engine runs as intended. iv had much better luck doing that than running webers or removing emissions. with that said propane or efi is the way to go for sure. theres lots of info on this site about tcases, i believe all 79-95 non turbo 4cy cases are 21 spline. turbo cases are 23 spline. 21 spline can be converted to 23 spline with marlins gear. i run a 21 spline crawl box to a 23 spline rear case.
THanks for the reply! So when you say you prefer to leave all the emissions stuff on? Meaning SMOG (air pump) Cat converter etc?