I know i'm late to the party, but I'm with the other guys. Rebuild the 302 with a better cam and heads, headers, and maybe a good bolt-up aftermarket EFI option that self-learns.

 

Let me clear up a little. The 302 that is in my truck is in good shape, what I dislike is he gas mileage the 302 gives. My truck is a 1995 F150 XLT with about 160K on it. Looks and drives good. That why I want the 300 six cyl in it, they last forever.

 

They last a long time but not forever. You will still be pushing the same weight with about the same 300 cubic inches. You must not expect miracles, or to ever recover the cost of this in fuel savings.