You can find some info on the tech section of Stovebolt about T5 swaps, mostly for AD trucks but good info. You can also find info on other websites like http://www.inliners.org/
You'll get overdrive with the t5 which will be a big help. I haven't done it but I plan to some day.

'64 swb stepside (gone)
'57 1 ton
'53 phone truck
'59 swb
'46 1 1/2 ton
'68 swb gmc