iam pretty sure the stroke and bore is different, but iam not sure if the crank bearings are different , if so you will have to grind the crank down to fit the 270 bearings, and maybe grind some of the block inside to clear,i only have the 270 block, so i can't compare the two, i was going by the local tool rental or lawn mower shop to see if the maybe they had an old 13 that was blown but ran out of time.