If your flywheel mounting surface and clutch face surface are not parallel its going to chatter. Or if you have got high and low areas on the clutch face side of the flywheel the highs hit the disk first during the engagement and chatter.
No burrs on the end of the crank or under the flywheel holding it from mating together flat ?
I would surface it and not worry about and VERY small imbalance that it might create because driving ANYTHING with a clutch that chatters is NO fun
If you feel like doing the math a 1" dia slug of steel 1/8" long is 13 grams
