360 stock intake manifold on a stock 318?

They make AR (Anti-Reversion ) headers to exploit the mismatch. I've even seen them on motorcycles and snowmobiles.

Been a while,since I have seen a new set of those.. Mid 80's,IIRC... As for the O.P.: I would do a stock 360 intake( or find even a Holley Street Dominator intake,or a SP2P Edelbrock,even...) .One of these,dual exhaust, & a distributor recurve,should get it done...