Before you cut the flywheel fins down, you might want to note the location and amount of imbalance on the stock wheel so you can compare to post-machined wheel. You already know the location, just tape little washers, etc., opposite to the heavy point until it balances. Save the weights and try them at the same place after machining. You then have the choice of duplicating the stock imbalance or going to a neutral balance. I didn't read about the factory set-up until after I modified my flywheel, so I couldn't try this procedure.