It's possible to get 300+ cubic inches with a 270, with some creative machining. With about 3/8 inch extra stroke, which is definitely doable, it will probably out-torque a 302. Pistons for a Japanese Diesel forklift can be used, instead of the horrendously expensive custom ones everybody thinks they need to use on a GMC buildup. There are lots of options available, for someone willing to think outside the box.
Jerry
