Well, the bellhousing end isn't a done deal yet. True the bellhousing will interchange and mount to the frame just like stock. The Monkey wrench is the Flywheel. The GMC flywheel does not interchange with the chevy flywheel. This brings up a starter issue, as the 6 volt starter you have won't work with the 12 volt flywheel the 270 has. You may have to convert the truck to 12 volts and run a 12 volt starter. If you are lucky, and the planets align just right, you might be able to find a 54-55 gmc 6 volt, 6 bolt flywheel from a gmc 248 that will keep your truck a 6 volt truck.
