Your stock CV carb can be made to perform well. Having said that, I have a Super G on my 103. Even on an E carb, you need to make sure it has the air bleed circuit added and an added bonus is the Thunder Jet third circuit. This really helps smooth out an S&S and makes it easy to tune.
If your guy says "What's an air bleed?" or doesn't seem familiar with it or the Thunder Jet, start looking for another guy. Seriously.
If you're looking at S&S carbs, then you owe it to yourself to look at XXX Carbs in Texas.
http://www.xxxcarburetors.com/
Read all about them and what they do to an S&S. Then make up your own mind.
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Seat, frame, stroker motor, paint, chrome, wheels, tires, road grime and a couple of old dead bugs. Fun meter.......PEGGED!!! 
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D.F.F.D
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