1972 Demon 340 engine mods

I don't see any notes about ignition timing or cam timing, but I suspect this is more due to the cam and rear axle gearing and having 3 speed manual than anything in the carb. But it is not clear if you are having sluggish response at low RPM's or high PRM's or at part throttle or WOT. If it is sluggish at part throttle response, then look elsewhere than the carb type as neither type would be in the secondaries at that time. (And of course any carb can be faulty...)