So I also have an E32, a 1990 735i. By next spring it will have a new E-Rod LS3 and a new 4L65E. This isn't a priority, but I've been making a little, slow progress on it, including tons of online research. Vorshlag doesn't cover this chassis, and their prices are crazy, but they do good, inspiring work.
I keep thinking about just starting with an LSA and 4L75E, but I need it to fit under the stock hood. Maybe if I dry-sump it? TBD.