I'm assembling a Mercruiser 485 motor to go with a NV4500 5 speed trans and a factory original transfer case. At 3.7L for a 4 cylinder, its compact and rated at about 200/300. Much smaller and far less expensive than fitting a 3.5L Rover V8, plus the engine rebuild is about 1/3 the cost. CHeck out this site talking about the Mercruiser motor:
https://www.jalopyjournal.com/forum/...banger.256713/