My experience for what it's worth: Bored my 235 .060" over (244 CI)--.020 milled off head (not much, but I didn't want to have to run 97 octane in it).
Split the exhaust manifold--I hate headers!--(not trying to start an argument--just my personal beliefs--I think GM knew what they were doing with the exhaust pre-heat chamber). Split manifold helped some, but when I found an old Edelbrock dual intake with a heat chamber and put it on--it lit that 235's fire!!!! Used 216 Rochester carburetors. Had heard all the horror stories about flooding, hesitation, constant adjustment, etc.--all I can say is that I've experienced none of this. Of course my best friend is a retired Chevy service engineer that came up thru the ranks--best carb man in 6 states in my opinion. When he rebuilds one he doesn't just throw new parts at it--it's done right with every adjustment correct. I think that's the big secret to a successful installation of dual (or more) carbs--every bit of linkage must move the same amount at the same time or forget it. As you may tell, I'm tickled to death with my 235 now. Hope yours works out as well----
