X2 on the 228. You could easily upgrade the 228 to a 248, 270, or 302 gmc motor. I know one stovebolt member in Napa that has an early 270 that would drop in your 42. An easy way to identify a gmc block are the 5 freeze plugs on the driver side, and a valvecover that has gmc stamped on it.
I personally have a hotrodded 302 gmc 6 ready to drop in my 1940 gmc.
Figure out what you have first, and then make an informed decision from there.
