Bigger carb is not necessary..Some carbs will work with either fuel, but most need to have the fuel passages enlarged..The main inlet hole, under the inlet needle, is drilled out to .083..All the other holes are doubled in AREA, not DIAMETER..This makes the carb work exactly the same as is does with gasoline..
The Walbro WT499 from a glow G23 works just as well with gasoline as it does with methanol..I put a WT499 on a G26, ran it with gas, got 9000 rpm..Put in a glow plug, changed to glow fuel, turned 9600 rpm..The engine idled and transitioned the same either way...The glow fuel was old so the % of nitro was unknown, probably 15%......