I have an email in to CSP-USA about the pump specifics .. you can get 3 types of pumps ... 1 for a 3 bolt gear (T1), 1 for a 4 bolt gear (T1) and 1 for a T4.
I agree on the Alu composition of the pump vs iron for sealing.
When I get the info back, I may choose the CSP T4 pump because I just want a constant oil supply for the engine .... not really concerned now that the heads/case may accumulate oil. I'll judge its performance this year and if unsatisfactory, there is always the Autocraft unit for next winters project !
Sandeep