You guys are quick! Thanks for the PN attempt Dan, I'll keep digging and figure mine out.

Jay, appreciate the pics, thanks. My feelings exactly on the size of the sprocket keyway, very strange. The amount of play seems unusual, but the part doesn't look worn or damaged in any way. My only thought would be that for some reason it was once replaced with a non-OEM part...??

Doesn't look like all that much is different between the two engines in the crank area. If the crank is really threaded that deep it seems like there's no way that I'm bottoming out the bolt, though I'll be doing this same test ASAP to see.

Good stuff on the key fit. Once I break mine loose I'll see how it compares.

Not to stray too far from the matter at hand, but once I'm back down to this point, would you recommend doing my front oil seal as well? I'd originally left it alone since it seemed to be in fine shape.