The manifolds will bolt up no problem but the 318 manifolds might have a smaller inside diameter. Take a gasket and compare it to the manifold and cylinder head to see if it matches up nicely to both.
What I have found from researching part numbers on Rock Auto is that for the vans, at least, they use the same exhaust manifolds for the 318 AND the 360, right on through the 80s... This would leave me to believe they are the larger ports for the 360 size and I SHOULD be just fine.
Maybe I could gain a little performance if I switched to the mid 90's magnum manifolds but they exit at the rear rather than down straight at the middle, so I would definitely have to modify the exhaust hookups if I went that route.
For now, I am going to just see what it all looks like when I pull the 318 and compare.
Fingers crossed, thanks everyone, for all the input, I will update when I get further along!
