Jay
Sorry I missed you at Legends. Hopefully we'll connect in person one of these days.
I'll take another shot at explaining the system that Pierburg recommends...
"When you wrote "the fuel coming out of the pump might meet too much resistance" did you mean the fuel coming out of the electric pump might meet too much resistance from the mechanic pump?"
Yes
In the diagram, 03 represents the new electric pump to be used what Pierburg calls a "pre-feeder pump". One that is used to refill the carb bowls prior to starting, but not while the engine is running. 06 represents the stock fuel pump...in my case it is the stock mechanical pump.
07 is the bypass line around the new electric pump. 05 is a one way valve that will only allow fuel to flow left to right in the bypass line. The bypass line is there so that if the stock pump can't pull fuel through the new electric pump when the engine is running and the new electric pump isn't, that there will be a path for the fuel from the tank to the stock pump.
The 05 one way valve is there in the 07 line to insure that when operating only the new electric pump prior to engine run, that the fuel being pumped by it doesn't take the path of least resistance and turn right when it comes out of the new pump at 07 and return to the tank/new pump instead of going straight ahead to (and through) the stock pump.
I hope that helps.