I'd like to help, but it is very dif to rd yr pst w/ all the abrev.
The olds swap is no different than any other v8 swap. I take it this is going in your 1960? As you are well aware any Buick, olds, or pontiac bellhousing will fit your engine. Most people would lack originality and put a TH400 behind that engine.
I'm not aware of the sm465 having a tailhousing mount, which is what you are going to need to mount the engine properly... 2 side mounts on the engine, and one tail mount on the transmission. I wouldn't reccomend a T5 to go behind your 425, but maybe a muncie m21 or m22, or a new process A833. Also a 94-97 Dodge NV4500 from a 2wd can be made to work. Really can't reccomend one transmission or another without knowing how you plan to use the truck, and what your skill level is.
