The fuel selector valve will select which fuel tank (or aux tank) delivers fuel to the sump tank. I decided to add a 1/2″ inlet to the sump tank, level with the fuel selector valve, which will now be the fuel inlet. This required cutting a hole in the back of the sump tank and adding a new hard point. The rear cutout was glued back in place with floxxy-poxy and leak-checked.
I will use one of the existing fittings in the upper corners of the sump tank for fuel return from the engine fuel servo, and simply cap the other one. I added an emergency shutoff ball valve on the fuel feed line to the engine.