Snails

So I have a 96 silverado 2500 8 lug with the 5.7. Motor runs fine but I am really wanting to put my built 400 small block in it with carb and maybe even swap the trans. It is my farm truck so I do not care about speedometer working or any of that. Just need it to run. I would like to keep the 4l80 but I do have a built 700r and also a 4 speed manual laying around that i could swap in. My question is how involved is it? Can I just remove all electronics and run it that way?