302 head exhaust port bulge and a '65 Valiant LH manifold

I had the same thing happen. I used a bare header flange between the manifold and my replacement head, that spaced it out far enough to clear.
Using the 302s on a 360 will give you a slight bump in compression, but you'll lose flow with the smaller valves and ports. Probably not too drastic on a "stockish" build.