Google Mikuni slide reversion. One example - http://harleytechtalk.com/index.php?topic=55089.0.
At least give John Sachs a call. John bored out my G-Carb. He also put in a Thunderjet which I removed on Saturday. I was too worried about the float bowl rubber hose failing and pouring gas all over the place. But the G-Carb jetted properly runs fantastic. MPG not so great but I ride very hard. 31/78 jets with a 600 cam. I also have the 30% bigger S&S air filter that fits under the stock cover with 1" standoffs.