Melling
I believe that problem came about because the SBC Melling good pump used to be the M55HV part number. But Melling made this number the cheap pump GM wanted, instead of making a new number for the cheap pump.
Melling made new series of good pumps with new numbers but dropped the ball not letting the racing public know.
There were also issues about going to cheaper gears that were not billet anymore, but made from compressed powder process.
Melling still makes good pumps if you know the correct numbers. If you bought a Milodon or Moroso you actually got Melling some of the time.
There is a Canadian stock car company that makes forged steel pump body oil pumps for SBC and BBC that is an alternative to more expensive billet pumps. Competition Products sells them.