The 54 GMC front motor mount will work on the 302. You will want to use the vibration damper from your 270 because the military used a 2 groove 7/8 pulley. Once you have the pulley off, you remove the timing cover you can see how it is attached. You will have to remove the cam which is no big deal. Just make sure you put the lifters in the order they go. They have worn in on the cam and need to go back in the same hole. You will want to use the 270 oil pan and oil pump because the government pan is too deep. The engines were mounted in front with the bosses in front that are threaded. You can fabricate a generator mount to fit the one on the driver side. There is a hump on the back of the block where the starter goes. You will have to grind it off to get a starter to fit. You will want to use the 270 distributor. The cam has a lobe for a fuel pump and the block has a boss where the fuel pump goes. It is possible to use a fuel pump gasket as a template and drill and die grind out a hole and drill and tap mounting bolt holes, but an electric fuel pump is the easy way. I have never known anyone to use the government carb system. The manifold is the same as the civilian that uses the Stromberg WW 2 barrel which is a very good carburetor. They were used by GMC and a lot of Chrysler products of the same vintage and parts are readily available. I just take the gvt carbs and governor of and throw them in the dumpster. The clutch housing, flywheel, clutch and all that will work from your 270. Don't forget to put a pilot bearing in the crank.