when you say 1/2" min return or won't get fuel pressure low enough, I get that the smaller return will be the restriction, but what pressure should it be.
Basically with a blow through turbo setup you need to run a high pressure efi pump, and an appropriate regulator and return to get the pressure low enough. I usually run 4psi pressure at idle
Your reg should be boost referenced and will increase fuel pressure at a 1:1 ratio with boost.
Because the pump flows WAY more pressure then 4psi you can see why a large return is important