This is an old thread, I know, but maybe others like me are researching this issues and maybe the discussion is worth reopening as Disco I and II and P38s age and engines wear out. Rebuilds with top hats cost as much or more than the value of the truck, so it doesn’t always make sense.

How about using a cast Buick 300 engine in place of the Rover V8? The 300, as I understand it, was the 215 case in iron and bored (I believe 300 cid is around 4.6)

as I understand it, the issues and difference are:

Buick 300 heads are, most commonly, cast Iron plus the Bosch and GEMS intakes are not a bolt up to them, however, I believe the orginal AL Rover heads will bolt up to the iron Buick block. I understand that the 300 is marginally wider, so a spacer would need to be made for each side of the intake to fill the void.

The Buick 300 uses the Buick-Olds-Pontiac bell housing bolt pattern, so you’d need to make an adapter to mate it to the ZF bell housing. The back end of the 300 crankshaft is longer than the Rover crank, so, the end of the crank would need to be machined down. Flex plate may or may not present issues as well. My question would be would a 4.6 Rover crank interchange with the Buick 300 without machining? I am not sure of the weight of the Buick block with the Rover heads, I know it would be more, but not sure by how much or if it would be manageable as is or with a coil spring conversion?

The front oil pump housing would need to be removed and swaped with the Rover (fitment issues?), to remove the dizzy and to have a cam position sensor, probably the timing gear/chain would need to be swapped as well, for the cam sersor pickup.

a crank sensor would need to be cut/added into the Buick 300. I believe the hole would be made in the bell housing adapter or by adding a gear (pick up) and sensor at the crank pully. I believe both engines have the same firing order?

i am unsure about issues with the starter (reusing the LR starter or making the Buick starter work, or somehow combining the two?).

So, has anybody tried this? Did it work out? What am I missing/leaving out? It would be a ton of work, but would likely make for a dependable Rover engine that would appear virtually stock under the hood!

BTW, I am not trying to start a war here. I know some folks think doing such a thing is an insult to HRH herself (and I can apprieciate that as well) but in my humble opinion, idoing this would be the closest thing to keeping an orginal appearance and could potentially be done cheaper and last longer than remaning the orginal engine.