3 speeds, most 4 speeds all have the same 1:1 final drive ratio. If you're looking for a way to include an overdrive the T5 is one way. Another may be to use the 3+1 A833 overdrive available in early to mid-80s GM trucks. Chrysler versions are very common but the GM versions still show up if you do a little searching. Some A833 transmissions use a unique bellhousing so you should research the possibilities for connecting the transmission to your engine if you find one with a non-standard bolt pattern. Some information can be found here:
http://67-72chevytrucks.com/vboard/s...d.php?t=670789
Also note for the future: A cutoff wheel can be mounted to a 90 degree die grinder to help remove stuck or junk manual transmission gears and shafts. I'm guessing in your old transmission's case the shaft spun in the case and created a ridge on the shaft. This may have damaged the case enough so it would have been tough to use but if it was made of unobtanium you likely could have cut the shaft out.