I am pretty sure they have mods to run full manual on the 4l80e...as long as shiftin all the time doesnt bother you.
They also have controllers priced anywhere from 1000 to 1900 dollars.
Anyway you you try it the 4l80e route is a pricey one.
Either spend it on gas or spend it on an OD transmission. I cant say it will take a long time for the transmission to pay itself off in gas the way gas keeps rising.
Things to ponder for your project.