6.2L L92 questions

[71rustpile]

Hey Guys,
I picked up a 6.2L L92 engine out of a 2007 Escalade a couple weeks ago and have some questions. Sorry if these have been asked before but I'm almost brain dead from searching for specifics. I bought the engine minus the accessories but it included the AC bracket. I bought a Alt/power steering bracket on Ebay that included the Alt, power steering pump and water pump so now I'm only missing the AC compressor. So I'm nearly set on my accessory drive, just need to get an AC compressor.

First question is what transmission would be ideal to put behind this engine? I would like to keep my stock gauges if possible. I think stock it had a 6L80E but I've checked around and they're pretty spendy.

Next question is regarding wiring harness and ECM. Should I be looking for a particular harness and ECM or go aftermarket? I'm putting this in my rusty 71 shortbed so I'm assuming some things could be eliminated from the harness??

Last question (for now) is what is everyone doing for fuel tanks? I would like to keep my stock behind the seat tank if possible but not opposed to just plopping a cell in (or under) my bed.

All info will be greatly appreciated! My plan is to finish this swap and have my 71 sideways by spring!!

Dan