Water pump pulley question

[Lynn Eades]

I pretty much agree with Rob's answer, but I doubt there is much wear on the shaft or in the pulley bore. If they look good (have them measured)
I would loctite them,but first.......
Another aspect to consider is how old the pump is. About 95% of engine failures come from cooling system problems.
All it takes to develop cracks, cook up rings (start burning oil), have pistons gaul (part seize) start burning valves etc. etc. etc., is what has already happened to you.
I'm not saying you've got any of these problems. As your engine is not new, it is somewhat less likely to have developed any of these problems.Time will tell.
Any how, the point is, maybe its time to buy two kits, and do both pumps.
Give your block and radiator a flush out at the same time.

BTW the flathead block has an entirely separate system for each bank, that is only connected by the radiator and fan belts.
That means if it wasn't for the water mixing in the radiator,the water in each bank would never meet.