[77 TRASHCAN]

Originally Posted by 78 WS6

I see where GMB has multiple pumps available, which one did you try?

Not sure. There was likely just one available for my 77 T/A (11 bolt, original) when I purchased it.

I worked at an auto parts store from 1985-1998. Somewhere in that time we had a line of strictly "new" import water pumps. I ordered a Pontiac, was surprised it was aluminum. Thinking I'd found an affordable aluminum water pump. So much for a bargain...
The life span on Mine went for several years, because, I seldom drove the car, as you intrend to with yours...
I sold another one of those exact pumps to a friend with a 70 GTO. His car saw more driving time. Seemed like about a years time on his before it crapped out.

I was in a hurry when the aluminum pump gave out.
I bought a "New" AC Delco pump. It was an iron pump with the stamped impeller. I adjusted the seperater plate for absolute minimum clearance. This pump was the 4th one I had installed. TIt was the 4th because, when I performed other engine repairs/modifications in that area, I replaced the pump, preventatively.
The iron pump with the modified plate cooled the engine exactly as cool as the O.E. pump. Man, wish I'd kept the O. E. pump. The other pumps had no cooling issues, just ran slightly warmer...