Water pump differences
I think that you can just switch parts from your 318 to the front of your 360. If your 318 has the timing marks cast into the timing chain cover then switch over the cover & water pump & all of your current drive accessories with their brackets, like alternator, power steering pump or whatever you have. If you have a bolt on timing tab you could probably skip switching timing covers & just move the tab over. You might have to use a file to elongate one of the holes in your crank pulley to make it fit the 360 damper. Use a positive stop in the number one spark plug hole to find TDC & make a new mark to correspond with the early timing tab. You might want to get a water pump specified for an AC car since I think it has more vanes in it & is supposed to help cooling but I'd probably try what I had first. Same goes for the radiator. Try it & see if it's enough. I'm kinda' old school down & dirty.
Switching to the later setup gives you access to a lot more options but it moves things closer to the radiator because the water pump has a longer snout. Lot's more involved if you go that route.