BIGBLOCK,
This is the right site. Sometimes these things take time. Unless someone has actually done this hop-up to their '58, all opinions would be conjecture.
Blabbing about stuff I know little about has never bothered me...here goes. Although this certainly wasn't a '58 truck, but rather a '54 car, I did have three 1 barrel carbs on a Offy manifold. There were no carb to firewall clearance issues. These were not Rochester carburetors. I used Stromberg units that were physically not as large, and smaller from a CFM standpoint (I think).
My thought is with two carburetors, additional engine modifications need to be relatively minor. In order to take advantage of the three carburetor setup, more extensive mods are desired.
My engine (235) was bored slightly oversize, had domed aluminum pistons, DIY port job, streetable Isky cam and valve train components. Dual exhaust, mallory ignition and lightened flywheel topped it all off.
The car started and ran fine as a daily driver. This was all done when I was in high school so I never paid any attention to gas mileage.
One of the members of this site did use a three carburetor manifold utilizing three Stromberg 97's (I think). This was in a AD truck and the installation required MAJOR firewall surgery.
Hopefully more folks will join in with better and more pertinent info than yours truly!
Stuart
