I've never heard of a Rover V8 cracking, but no doubt someone has managed it. As I recall, the capacity can be increased with a longer stroke crank. Plenty has been written about Rover V8 capacities over the years. Heads vary in efficiency.
The biggest weakness of the Rover V8 is the accumulation of black tar over the whole of the inside, so first job is to take the oil filler cap off and look inside. If the visible rockers are black and tarry, the whole inside of the engine is likely to be that way. It can only be controlled with regular oil changes, and minimising cool running.
The engine I took out of my MGBV8 after 100k miles was totally shot. The tar varied between thick sludge and bonfire toffee. It ran well, even though two cam lobes were gone completely. I only did the last 10k!!!!
