360 into 64

Grinding the boss on the head will give it the clearance you need. As far as blowing out gaskets, i had that problem. I had to have the manifolds trued up by machining the flanges. That created another problem... The manifolds where up against the head and I had no more meat to cut. So I used 1/2 aluminum plate, used a 360 exhaust gasket and cut out 3 spacers. Made a transition from the 360 port size to the 273 exhaust size. Pluged the smog ports with screws and jb weld ground smooth. Used two gaskets, 360 on head, and 318 on the manifold. 5 years no leaks yet.