I was adjusting idle and tune on my HIF6s yesterday - mulling over the differences between the front and rear carb on this model versus the HS6, when it occurred to me that the #1 carb has a in and out fuel pipe, while the #2 carb has just an inlet and a solid boss where it could have an outlet pipe. Some of us (me for sure) have had issues with our needles sticking and carbs overflowing and with too much fuel pressure from later style pumps (e.g my West German Peirberg). I once had an overflow with the ball-bearing type jets - which is one reason I have HIF6s on my car.

Why couldn't we drill out the matching boss on the rear carb and install a return line to move excess fuel back to the tank, as is done with a fuel injection setup? This would certainly negate the problem with too much fuel pressure and likely negate the issue with float bowl overflow. It might even improve fuel economy. At the least, you'd end of with a working FI fuel system for future conversions.

I suppose a pressure regulator might be needed, but with a constant mechanical pump, it might not.

Any thoughts or warnings about doing something like this (aside from risking my nice working carbs?