350 Starter holes drilled incorrectly?

[Gibson]

Ok, got off the phone with Powermaster (really nice folks) the model I have looks to be a white label version of one of their starters - possibly an older model. At any rate, they helped me anyway which I thought was cool.

They have seen this issue before on sbc's and confirmed that it is very possibly just a case of stacking tolerances. So my block is off a fraction, the crank might be off a fraction, etc. All those add up to "too much gap between the starter mounting holes and flexplate". The tech said that on a gear reduction starter, you really only want the teeth to engage about half of the width of the flexplate, so I don't need a ton more throw really. Unfortunately there is no shim of the type Desert mentioned available for this starter.

What I'm thinking of doing instead is modifying the pinion gear on the starter. On the one I have, there is at least a half inch of smooth bushing area on the tip of the gear. You can see that in the pictures - it is pretty large. I'm going to precisely cut a thin disc of that away and move it to the back side of the gear, effectively moving the teeth forward about 3/16. Whats the worst that could happen, right?