Water & Fuel Pumps

[canonball]

Hey guys, both my water and fuel pump are on their way out and I wanna make sure I'm grabbing the right parts to replace them. Engine is 305 V6 in a '63 GMC 1/2 ton.

There's a review on this fuel pump that says the gas line fittings provided with lit were smaller than factory, 5/16 instead of 3/8, had to purchase separate fittings and then it worked. That sound correct?...
https://www.summitracing.com/parts/a...rview/make/gmc

This looks like the only water pump Summit carries for the 305 V6...
https://www.summitracing.com/parts/g...tions/make/gmc

My belts look like they're in decent shape but if I'm removing them to replace the water pump it's probably a good idea to go ahead and replace the belts as well?

First time replacing these parts, I suspect the fuel pump is fairly straight forward, found a similar tutorial online and looks like I need to keep the plunger up and make sure the new pump attaches to it properly when re-assembling. I'm going to need to drain the coolant when replacing the water pump right? Anything else to look out for?