With a 78 m2 setup, 2.3 - 4sp in my 76 sedan. I'm looking at just replacing my 4 speed with a t5 rather that breaking it open to fix the reverse issue. I can get a 85 xr4ti t5 with a hydraulic clutch pretty easily. Will my 78 m2 bell and cable clutch work with this t5? I know I may or may not, have to adjust my drive line, and elongate my shifter portal. Any help is appreciated.

I'd like to see what you do. You might want to start a post in the Projects forum.
Can't help you with your questions though.
Russ

And..., here is a the way my '88 T-5 was used with an '86 bell crank.  Yes, I did use the stock Pinto cable.  The main issue is the interference of the cable and the crossmember. It is remedied simply but elevating the cable with a bracket using the existing hole for the cable.  In my case I put a small, anti-rotate tab on the bracket in case it ever came loose. Because the bracket moves the cable outwards, as well as upwards, there bell crank benefits by slightly bending it outward to align.  The other caution is when one gets the bell crank bell housing to remember to get small intermediate cable.