It will bolt up just fine. You may need to consider whether the T-5 is strong enough for your application though. The T-5's are okay behind a stock 5.0 pushing 225 horsepower. Somewhere around the 300 horsepower mark they begin to have catastrophic failures. (Actually it is more likely a specific torque number, but I don't know the number off the top of my head)
On a brighter note, it is my understanding that the clutch pedal will slide onto the existing pedal shaft of automatic cars of that era, so that may help a little bit. You may want to look at shifter location on a Toploader and compare that to a t-5-I am pretty sure you can make it work by trimming a half inch off the right side of the transmission tunnel opening if your car is a floor shift.
I went with a T-45 to replace my toploader and bought it from Keisler engineering. It is stronger than a T-5 and Keisler does make some internal improvements. Works great and a 5 speed turns the car into a pussycat around town if you want to drive it easy or a monster on take off with the lower first gear ratio.
The clutch cable setup for the T-5 can have issues with burning on the exhaust, so make sure you route it carefully and insulate it where necessary.
Personally, I would stick the T-5 in there and take my chances if you aren't running it at the dragstrip.
