Where to get jet kits for RM250

I'm going with a G3 / Mossbarger reed valve assembly and torque space. Need to re-jet the bike. I can't seem to find jet kits for 2-strokes nor do I know the correct carb at this point (sorry, just purcahsed the bike...98 rm250). I think I'll need to go up 5 mains. Source? Is it standard to buy individual mains at dealers?

That's all I'm wanting. So just go up to the local dealer then?