Oliverdude, from what I have figured out over the past couple days working with the Saginaw pump, they put out probably close to 2 GPM depending on rpm. I am running mine at slightly under 600rpm, and probably have it down under 400PSI. At that rate, my 1/2HP motor seems ok with it. At that rpm, it will also not always "engage" or "prime" if I have had it apart to make an adjustment to the pressure control. I have to put on a bigger motor pulley (about 750 pump rpm, maybe) at which point it will run briefly, the pump will engage, and stall the motor. Then I can change back to the smaller pulley and everything chugs along working fine, including stop and start again without further "priming".
What I'm getting at, is if a cheap 1000psi pump works for your application, the volume is pretty good, but you might need "a few" HP to run it. Since you're looking for pressure, there is not a way to reduce the flow to reduce HP requirement, unless by an external flow control and return line. As mentioned, there are aftermarket gear pump, PS steering pumps rated for slightly over 2kPSI. The vendors might be able to tell how much HP one absorbs. OTOH this Chevy pump cost $15 out of the local Pick-a-part junkyard so cheap to experiment with.
BTW, everything works fine for the mill, now. Need to find a pressure gage to feel secure about using the stops, though.
smt