a stock 350ci dont need a carb any bigger that a 600. GM has a crate motor they sell. Its a 260hp 350ci. The people who designed the motor suggest a 525cfm carb. Hmmmmmmmmm
I would still go with a 600 though. My neighbor has a 350 producing about 330hp at 5000rpm 380ft-lbs torque at 3800rpm and is running a 625cfm road demon jr. This is after trying to bigger sizes. I feel 305s arent the best for all out performance anyway so why not go with TBI? Very dependable. I am not dogging 305s in any way. I had a 305 TPI in my Firebird and until I pulled the motor I swore it was a 350 by the way it ran. Beat many Moostangs. And as far as carbs being less trouble I would have to disagree. This is why I say go with what you know.