Here are a few tidbits:
- A Buick 350 is likely to bolt directly on in place of a Rover V8. However, the last one went off assembly line in 1980, so it would not be a legal swap. I'd still consider doing it, along with entire Rover EFI setup. It would take a lot of tweaking, but it might work. A cast-iron Buick V8 is a beautiful thing.
- A Buick 3.8V6 might bolt on as well. This is a gray area, for all of those were used in front-wheel-drive applications. Many Buick boats of late years came with 3.8 with a supercharger on top of them - that'll put it far ahead of the Rover V8.
- Another option for a swap: Ford 4.0V6. Surprisingly, it has better low-end torque than Rover V8 of the same displacement. The AWD Aerostar I once owned (same curb weight as the Disco) felt faster off the line, and more powerful on the highway, than the Disco.
- Max: about Turbo 400. It's a great and indestructible transmission, but it has 3 gears, no lockup torque converter, and is a huge power hog. Like Chrysler's 727, it sucks about 45 horsepower on average. In big jeeps and trucks, it had a low-rpm (~1500-ish) stall torque converter - which has mixed consequences on driveability. Namely, my jeep's turning 3k rpm at highway speeds because the TC is completely locked up, you'll hit the steering wheel if your foot slips off the gas pedal because of engine braking, and you're looking at 10mpg regardless of the type of driving.
In any case, I would not mate a 4.3V6 Chevy with a TH400.
