With that setup if you start the lift engine first the thrust engine will flood. And when it's running, even though you have the head tank, hydraulically it will still see the fuel lift as being from the main tank.

A real can of worms.

Two ways that have proved to be easy and both work well:

1) Install a Perry VP-30 pump on each engine, and use separate clunks in the main tank - one for each engine. The muffler pressure ports would be plugged or left open, and the tank vented to the atmosphere.

2) A full pressurized fuel system using either the Iron Bay or Cline regulators. Still with two clunks, but in this case both engines would be feeding muffler pressure to the fuel tank through check valves.

The Perry two pumps would cost roughly 1/2 the price of the Iron Bay/Cline system.

In both cases the head tank would add nothing to the reliability, and would raise the center of gravity. Best left off.

Bill.