Oil pumps again...

Hi

I wonder if anyone had experience comparing Melling 63HV and Milodon 21814 pump body with lets say HV standard pump cover? Does it make sense?
It seems that there is no information on Milodon, weather its worth to go with it, what is the size difference? What is the drag it creates vs the HV pump etc.
I tried to see whats the GPH rating for HV pump but I failed to find this information.
Any pros ad cons price aside? I saw some claims regarding power gains using milodon vs HV pump as well with more low rpm oil pressure. Any real life information that you could share?

Thank you.