Dave,
You are going to have problems with that flywheel after shaving that much off the face. 125 thousandths is a bunch to take off the flywheel face.
1st, the clutch hub disk springs will most likely hit (rub) the flywheel bolts (even the really thin head ones). There really isn't much clearance between the bolts and the hub springs on the clutch disk anyway, and if you cut much off the face of the flywheel you will run into clearance problems. You could have the machine shop machine the internal portion of the flywheel center hub area down an equal amount, but I think this would weaken the structure of the flywheel too much, and your legs could be really expensive to re-attach.
2nd, you will change the clutch release geometry some too. This is of course is something that can be dealt with by the adjustable linkage pieces, and a different clutch pivot ball, but do you really want to go down this road?
I would follow OMT's recommendations about using an aluminum flywheel. I have a McLeod for my next engine, and the GP has a Hays steel flywheel in it now. The steel wheels can be lightened somewhat by machining the backside of the flywheel, but not normally the face. I would not recommend doing this to a factory flywheel.
Good luck, and good launching!
K.
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K
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