I built the E4OD that is in my 84 E350. I did it "by the book". I spent three days assembling the transmission, and two days on the valve body kit. I built the trans based on an update book.
Had I started another the next day I probably could have finished it in one day. And the tenth ten days latter about a half day. I relate this to give an idea what professional labor time really is.
The general guide for building an early E4OD is to build to 1997 level. If you already have a 97, your are just replacing worn parts.
My van weighs 9K# and has done many cross country trips.
I get triple disk billet converters from Roadrunner, Phoenix, AZ; $400.