6L80 cane found for less than $1000. DOn't know what the condition it might be in. See
@bloc 's posts reg the work his needed. They are not all perfect. The remanufactured ones are great. The rebuild ones, not so much.
I replied to his posts with a few links you might be interested in. Good to keep in mind for the future.
The 6th gear on 6L80 is way too tall. It will drop the engine RPM in a lower power band and you might experience some gear hunting on the freeway. If you plan on driving 80+ MPH it's possible it will be just fine.
It will work great with 4.88 gears and 35"
(Based on paper research, not actual real life findings!!!!!!!!!!!!!!!!)
Stock gears will get you 2.74 final ratio, which will actually be lower with 33's, 35's, etc which will make it shift like crazy between 5th and 6th due to lower RPM and lower engine torque.
A 4.88 gear will bump it to 3.26 ratio which in turn will be a little lower with larger tires too, and it might just put it in the sweet spot Toyota designed the engine to be at freeway speeds... 3.09 ratio for stock everything.
I really have to mention it again... this is based purely on what the paper calculation show, not tested in real life.
If you want to keep it as much Toyota as possible, then a turbo 1FZ and a 6L80 tranny might get you partially there. At least it's not a full blown GM V8 swap and it will cost you less as well. With a V8 swap you are looking at $25k-$30k range. Turbo plus tranny and a lot of work done by you, might put you in the $10k ball park.