Swap out the 270 I-6 for a 302 I-6 ?
Jump up to the 60'-74' GMC Big Block V-6's 305ci -478ci ?
Not sure just adding a larger carb will make the 270 do as you want . . . Its also a 60 year old 1.5 ton truck with a 6 cylinder Gas engine, So its not going to get up and go like 6 year old 1.5 ton truck with V-8 turbo diesel . . .
Mike
