Single or double?

OK if the timing cover and water pump are both '70, then that can put the fan close to the radiator core and top tank.
When you get to the A/C you want to figure out a way to have a fan shroud.
More immediately see how the lower hose is routed. This is an issue with later water pumps on pre '70 cars.
I've solved it a couple ways. Currently I've got a '70 lower tank on a '68 top and core - which works great.