the chain is only as strong as the weakest link. so if you put in a hot cam but run a stock carb, the cam really is not doing much of anything. also as Mass said, you can't really tune a stock carb with different jets. also stock exhaust will hog tie the set up too... an open exhaust would be ideal to let the whole system "breathe".
now as a compromise, you could run a Dellorto. that would be "period correct", opposed to say a 22mm xr75 style pz22 slide carb (which is what the majority of the people here are using.) The Dellorto is awesome, probably better in some respect to the pz22 carb. but the down side is cost. now you don't need a Ua19 dellorto (as used on Rupp Black Widows)... in fact i would not recommend that carb as it's really expensive. but you can get 16mm to 22mm dellortos on ebay often for cheap. parts are a bit of an issue but for the most part BlackWidowMotorSports.net sell everything you would need. I have used all the dellorto sizes from 16mm and up, and they all work great. like *way* better than any stock tecumseh carb. even a 16mm dellorto works great, though 18mm to 22mm is ideal. in fact i have NO motors with a stock tecumseh carb... those butterfly carbs are a joke...
now if money is a factor, the pz22 carbs made in china and available on ebay are pretty awesome, for all of about $20, and often even come with an air filter! you can't beat it. and often they are jetted correctly right out of the box (not always, but often.) i would buy a set of M4 jets (#85 to #95) just to have, they are cheap on ebay. you do need an intake manifold. but again if you are on a budget, you can mod the carb a bit to fit on a stock tecumseh intake manifold. not the best way to go, but it works. and if you don't like the result, all your out is a $20 carb and a $12 db30 style throttle (yes you will need a new throttle assembly with the slide carb, as your stock cherry assembly won't work.)
if you want to read more about this stuff, including Dellorto carbs, check out this link:
http://www.pinrepair.com/minibikes/tecumsehmb.htm#carb2