I was able to buy new o-ring that I thing will fit the old filter assembly, I want to make some tests before deciding which way to go.
Saw also a holley in tank drop-in option, for the stock tank. they also have the EFI capable stock-type tank (only with a recess for the efi stuff) with the pump and sendng unit, this one is a return type assembly.
I will make some tests on the weekend to see if the floaters are not working properly, or if I overfilled the sump and this is causing the issue. May end up moving the floaters from the old pump into the new one or something like that before attempting to buy a different system.