External Durso question needs answering

I went to Lowes and picked up 1" fittings and pvc for a durso. I want to do an external (elbow inside the tank, the rest outside) because I can't drill the bottom of the tank and stand to get to the sump, so everything has to run outside.

I have read around and some say 1" Durso can pull ~600gph when the bulkhead is 3 inches under the surface of the water and some say otherwise.

I have the drill bit and bulkhead already ordered so waiting on that to come in to drill the tank. Just looking for Durso advice, since it is going to be an external Durso and I haven't found much on it.