99% of the time, the stock 32.5 pilot is correct in the stock carb.
I've seen FMF's require from 270 - 310 mains depending on other mods, elevation and temps, you'll porobably be safe to buy those jets.
IF....you were jetted correctly and plug chop confirmed, increase the main jet 1 size per 20 degrees drop from what ever temps you last plug chopped at, then plug chop again in the current temps after increasing the main jet size.