I did a T-5 swap on my 60 (replacing a 4 speed) a few years ago and am very satisfied with its performance in all respects. It is quieter than the 4 speed, shifts easier, and makes a huge improvement at highway speeds.
You will need a T-5 from a 92 or earlier S-10. This will bolt to your stock bellhousing after you slightly enlarge the holes in the T-5 case to clear the mounting bolts. The only difficulty is that its input shaft and front bearing retainer are too long. If your time is cheaper than your money, you can shorten the shaft (it's just the pilot) and the bearing retainer. If you have money to burn, you can get a spacer plate that eliminates the need for any mods except for the driveshaft and shifter hole.
http://hamiltonintakes.com/products/s10t-5-adapter.html
Keep your stock bellhousing, clutch linkage, flywheel, pressure plate, pilot bearing and throwout bearing. You will need to replace the clutch disc with a 14 spline disc from either an S-10 or an Astrovan. Use the Astro disc if your pressure plate is 11" and the S-10 if it is smaller. You MAY need a longer speedo cable, but try your old one first.
If you are replacing a 3 speed you will have to cut a hole for the shifter and get a shorter driveshaft. If you are cheap like me, install the transmission, measure for the shaft length you need, and head for your friendly local salvage yard with a tape measure. This will cost less than paying a driveshaft shop to shorten your stock shaft.
If you have questions about anything I forgot to mention here, please ask, and I will try to answer them. Unfortunately, I didn't shoot any pics while I was doing the swap.
Ray