Bit of an update, I haven't been able to get a lot done due to being back at work this week, but I did finish modding the sump:
I installed it but even with the mods it was tighter against the diff than I would like, so I raised the engine mounts a bit. This has given me lots of clearance, but caused another problem, the engine is now canted backwards too much, it's almost touching the bulkhead and the prop angles are more than I'm comfortable with due to the angle of the engine and transmission. I intend to solve this by simply dropping the entire front subframe by around 20-25mm with some spacer plates. This will bring the engine and driveline into a more acceptable angle, and as an added bonus it will help to bring my front CVs more into line, I've never been happy with the angle of them since doing the 2" lift so it'll be better all round. I'll lose some ground clearance, but I can live with that.
Also, how easy will the electrics and dials be?
I have the complete 1UZ loom and ecu, I will just piggyback it in the Mitsubishi loom, leaving the Mitsubishi ECU to run everything else. The dials should be pretty straightforward, according to somebody who's done this before the tacho will happily work from the Lexus RPM output, and the temp gauge even works correctly from the Lexus sender.