Beagle - there's a slightly different dynamic here - we're not talking about a few thou here, we're looking at half an inch...
Your Tracker takes a 15" rim stock, so what you were doing is grinding to clear an aftermarket 15" rim.
The GV brake requires a 16" rim to clear, and not all 16" rims will clear - I don't see it as being possible to grind enough material for the Samurai's stock (or aftermarket) 15" rim to clear without rendering the caliper useless, and that is assuming that it can bolt up to the knuckle.