I was told at the Holley EFI class that I also need a dip tube to reach below the surface of the gasoline to prevent aeration if returning straight to the tank.
wasn`t a problem with carbs but that's 7psi vs. 43. so...

I ended up running two -6 returns to a single -10 and placing it part way up the tank away from the pickups.

I can't see any way to run it back to the Hardin filter heads without causing heated fuel or some weird fuel pressure issues especially with the amount of fuel the A1000 will move.

Speaking of FP, what should I start out with pressure wise at idle? I am running a regulator that is 1 to 1 boost reference. I believe the factory is 43-45 psi for MEFI 3?

Ive done it this way on multiple projects and never had an issue.

Good to know, I'll try it out one day as the regulators are mounted to the filter heads.