This service could be satisfied by a centrifugal. Either Sundyne or Roto-Jet could meet these conditions in a single stage machine. However, for the Roto-Jet, you would need to be sure that there were no heavy solids (sand). The Sundyne would also have problems with solids, but would be less sensitive than the Roto-Jet. We also use a Sulzer stacked diffuser multi-stage pump is a service very similar to this (95 gpm at 1000 psi). It has worked well and it is more efficient than either the Sundyne or Roto-Jet. If I was building a new unit today, I would definitely not choose Sundyne. I would evaluate the Sulzer or Roto-Jet options based on suction conditions, efficiency and up-front cost.
We have used positive displacement (piston) pumps for services such as this. All of them have been removed because of poor reliability. But, our services run 24/7 for at least two years at a time.
Johnny Pellin