318 low budget build
How fast do you want to go? What cam/converter and gear do you have now?
I wouldn't run 302's if you want performance- I've ran 302's and 587 360 heads- the 587's run much better when the combo is right, both heads used 1.88/1.60's with the bowls ported and the runners cleaned up.
My old 73 Duster with a 318 and 360 heads was probably making 260-275hp with the MP 2,500 converter and 3.91's I was running 8.6-8.7 in the 1/8 @ 80-81mph. It was just a thrown together combo using was I had laying around- stock 318-4 longblock with a comp xe268, M1 single plane, 600 carb, recurved stock dist and ignition, small headers and 2 1/4" duals. At the time it was my daily driver and got 14-16mpg on my 110 mile daily commute.