Snapped Belt Damage?

[C.A.R.]

For selling it on?

I think if you have a known 'borked' engine but one bare one which is fine (seemingly) then the hassle of swapping the ancilliaries over would be worth it. Last thing you want to do is to replace the head (pressumably gaskets etc. symultaneously) and find it knocking from the bottom end.

Maybe worthwhile investing in an engine stand? That way you could dress the good engine - the knackered one can sit on a block of wood or something!