Great info guys, that's why I like asking things here, even if they're
only remotely metal related

Never thoought to check the back of the hubs to see what's there and
you're absolutely right, there are bosses at the six bolt locations
so re-drilling is not a viable option.

Found these adaptors, seems a little pricy for a hunk of 1" think
6061 with a few holes and 5 studs:

http://www.adaptitusa.com/index.asp?...TS&Category=10

Doesn't look like there's any shoulder to match the wheel to help
locate it, and what about using aluminum for this part, doesn't seem
the strongest to me.

How about making an adator from some sort of steel with a shoulder to
locate the new wheels? What would be a good material? That way I'd
keep the standard hubs and bearings...

Looks like the offset will work OK.