Maybe the manual is correct - 2 degrees at the cam = 4 degrees at the crank?

I do agree with you, Dave, that changing the chain is the safe thing to do. I'm just intrigued why they would sell such extreme offsets - as pointed out above, that's beyond any conceivable manufacturing tolerance for a new engine.

Has anyone ever come across a new 617 engine with offset keys installed? Probably impossible to learn at this late date.