350 sbc mate to t56 and eventual ls / lq swap

[71C10Guy]

I have a 350 swapped 71 c10. I would like to swap to a manual and I'm willing to do the work. Honestly getting it in the truck is seeming like the easy part at this point. As far as I know a t56 bell housing should fit both the 350 and almost any ls / lq I would eventually put in.

Now that I'm looking more into it, I'm wondering about spline count, depth, and rms differences.

I don't remember what rms the block that is currently in my truck uses. I know worst case I have some spare one piece blocks that I could build and swap. But at that point I may just do the engine and trans swap in one go instead of building a 350 I want to swap out anyways.

This may be a simple question that has been answered a lot before, sorry if it is!
So is there am input shaft spline count / depth I should specifically look for that would work with both a 350 and an ls out of a camaro / firebird? Is that even possible?