Exploding water pumps? Difference in early 273 water pumps vs later 1970s 318 pumps

Slantsix64 said
A/j would I be okay to run a 6 1/4 crank pulley and a 6 inch water pump pulley

That would be overdriving the water pump by a small amount, about 4%

The stock non high performance is under driven by about 5%

The HP cooling was over driven BUT they used a 6 vs 8 vane impeller ( don't know why)

As to your question... I think you will be fine.