i thought of my old 911 as soon as i saw those carburettors. it had triple choke webers on it and i loved them.
the phenolic blocks don't seem like a bad idea, but i would think aluminum might be better. i've only used the phenolic as heat protection to prevent boiling the fuel.
you can't really polish the inlets of those can you?
s1 fulvia sport, s3 appia vignale