i think the question is really how much do you want to spend on it? 500 1000 1500 2500 4000??
you can hit the 2500k mark pretty quick. if your cylinders are fine and your tight on funds get the crank rebuilt or replace with hot rods 350cc and get the cylinders re worked and rebuild the motor. even stock porting with a fresh top end and nice crank will run better. in the right hands a 150 buck "cheapo port" will do wonders also.
if you do serval 4 mill you have a lot of other things you need to get besides carbs. billet basket, heavy clutch, transmission modifications, a head, porting in my opinion some case work and upgrades... let alone does it still have torrs? things like that add up.