No gasket required when there's two machined surfaces..... that was the idea anyways. You do whatever makes you happy. You have a gasket for a DII's plenum. Motor flush won't do too much to the baked on carbonized oil, no miracle in a bottle will clean that up, tried many times. The only way to clean up the coal is the old fashioned way so it looks like this......

One reason your oil is so dark is due to ring blow by.... sorry.

 

Thanks yea here is the gasket style they gave me, they need to update their parts manuals.

You think that's blow by? My guess was because it was leaking and the last owner was late adding more oil, had the same thing with my old Tahoe when it was burning oil.

 

LOL, I figured.......parts palaces are notoriously off when it comes to Rovers.

Same with my work truck, 03 Chevy, never have to change the oil just the filter. Yep, the Rover is set to run rich and that makes coal that eats the snot out of everything early in it's life. There is a thing in the passenger side valve cover that is the British equivalent of a step valve, it's the PCV, it will be like a solid object not allowing blow by back into the air stream through the plenum. Check it, clean it! I'll say that most folks who've owned a Rover never had a clue about maintenance and these really require allot of attention to make them last, not something to overlook. You being on the other end of a long stream of forgetful owners will have a hard time getting it back to factory due to the wear and neglect. I spent 8 years of my precious life trying my best to right the wrongs........ in the end the Rover beat me.