I guess the short answer may be "anything will fit with varying degrees of effort and frame mods".

But are there engines, such as a DR, perhaps, that have the same mounts?

Why?
I bought a parts bike from SteveSavage from this forum. Steves bike had sufferd some top end problems, possibly a slipped cam chain or dropped valve. The piston top has some kool war wounds. Steve unfortunatey dumped the entire top end. But that is pretty much all that is missing from the entire bike.

So as LS650 engines are fairly uncommon here in Brisbane, Australia im considering options:
A) Try locate another top end and barrels, and ship or a complete engine locally.

B) see if I can buy a DR engine and put that in (if its a close match)

C) see if I can slot an XS650 engine in.  (I have one in my shed)

Has anyone here done an engine transplant?
I would be keen to hear what engine you put in and how much effort..

Cheers,
'G'.

I would be more interested in what other bikes could accept a Savage engine with minimum problems.

Aliassmith