forum.audiv8.com Foren English Talk A8 (4.2 ) motor into V8 (D11)

AEC cars are rare in UK. More common over on the continent, I think.

Audi A8 4.2 uses ABZ engine. It appears to have a number of external parts in common with ABH/PT. So dimensions wise, it should be straightforward.
I was considering getting an ABZ to explore this route. But if we are talking about making engine mounts already, then, I don't know.