Best 416 small block, 727 auto, TTI installation order?

Coming up from the bottom isn't an option now. Still a roller.

As for going from top, it sounds doable if I lay the headers in. I took out the tranny first, then the engine. I may do what you said and go with headers, engine, then tranny. I am having a guy with a 2-post lift helping me, but as you can imagine, he hasn't done an a-body like ours before.