318 cylinder head upgrade

675 casting is a good one.
Just mill those .026 to remove 5 cc , shoul be about 63cc at that point, 1cc smaller than a 302. Save yourself the money..cause the 302 does not flow anybetter and any other head.
And for what it's worth... a 273 head is 66.5 CC's roughly. The exhaust port also has a better floor on the 302, 675, 163, 593.