I stumbled onto this yesterday. Two part video of the Flying Dutchman’s rebuild of a “Chevy 6” water pump. I think it’s probably the 216 style relevant to this thread. Worth a watch. He actually does machine work on the internals to true up the sealing surfaces. Claims that the rebuild kits tend to leak if you don’t get the runout below a couple thousandths.
I have no direct experience to confirm that he’s correct, nor to refute him. My initial impression is that his rebuild cost is pretty darn cheap for the level of work he’s doing here. Best I can tell, a rebuild kit to do it myself is roughly $75.
