The 4v head flow good numbers,.. they always have even back to the B heads. But they are still only run a 170cc intake runner. Ford used IMRC plates in order to compensate for the lack of low RPM velocity in early versions of these heads. FR500 heads are only 160cc heads. The latest heads IIRC are 177cc but they use 'VTEC' which helps give them a cam profile for low end torq and then another for high rshared_pm HP. I've yet to see a SBF cam that works well on both ends of the spectrum.

The lack of velocity using a larger head on a small engine will cause low end torq to suffer, but it will definitely make good numbers on the big end. The right cam choice will be cruicial for good street manners. I think he will have to give up some of the top end hp in order to maintain a good idle that doesnt sound like a machine gun.

Going with EFI should result in a smoother idle than with a carb application. The IAC is constantly trying to smooth out the idle and with the speed sensor working properly it should bump idle during coasting so there 'should' be less bucking and kicking with EFI.

I guess it have to come down to trial and error as far as cam choices go. I can provide a video of how a carb'd version with 185 heads and a NX274HR cam sound. I experienced low rshared_pm bucking with both EFI and carb with this particular cam.

Hurst