I have a 1972 350 that i am rebuilding and i would like to know what kind of water pump would be best for it. And why certain water pumps are good for some setups and others not.

Not sure what you mean by "certain" water pumps? Do you mean electric/mechanical? If you're talking about a good old fashioned long water pump, which is what you need, there really isn't that much of a difference. If you have a high HP application a high flow unit might help. I've got a $20 water pump in mine. If you want aftermarket make sure it has the accessory bolt holes in it.

ok, i was just seeing if any were better than another. thanks

I am using an edelbrock victor jr pump, and it keeps my 468 plenty cool, stays right at 180 all day. And this is with a stock 2 core radiator. Well worth the money I think

When I rebuild my big block this year it is getting a new Milodon high volume, long, cast , pump with a matching 180 thermostat,I was told these are supposed to be the best belt driven aftermarket water pumps.
Guy