Maybe I've learned a good lesson . . .

I like TT5.9 (Mikes) answer.
But me? I'd put a cast 4"stroker kit in the 318, get 390-395 inches, throw on some speedmaster heads, preferably bought from a black friday sale, use the intake you have, with maybe some brand of 750, use the exhaust you have. If you REALLY want to get into it...... an overdrive with a gear change. Should get you an easy to live with 400hp, 400 torque.
I would not do a 440 swap, too many things would need to be acquired and /or changed.
If you WANT a 440 powered car, to go fast in a straight line...... I'd find a slant six Duster and swap a 440 into that.
My opinion only (from a guy with a 440 swapped /6 car)