C to C is 270mm, +0,-3mm or 10.6 in +0, -.11
Offset is 5.5mm +/- .5mm or .217in +/-.020
Offset is measured off the backside of OEM clutches and for OEM belts. If clutches/belts are not OEM the offset measurement will likely be different and C to C could be aswell.
The front frame tubes on these sleds tend to get bent (bellied in the center) over time from hard landings. The engine mounting plates can also get bellied or broken. This can throw off alignment and make proper alignment tough to get back in spec at times. Crankshaft/jackshaft centerlines should be parallel and perpendicular to eachother. If things are bent they probably won't be.
Good Luck, opsled