In front of the switch would be the easiest, but closer to the tank is best for pushing.
However, hopefully some of the members here who have mounted their pumps farther forward will chime in with which pumps worked best.
The Carter P4070 is a long standing go to, and seems to pull pretty well. Oddly enough though, even some people have had reasonable luck putting an electric fuel pump as far forward as the engine compartment. But no pump manufacturer that I know of recommends that, and most people have issues when they do.
Not sure why some do and some don’t, but that’s the world of automotive modification!
So, you still have dual tanks? If so, your front auxiliary tank should also have a vent tube. You will want to tee that into the line that goes forward to the charcoal canister as well.