Cross member isn't cut. They just cut a piece of flat steel and bolted it to the top of the cross member. Does the GMC in 58 have a different cross member than the Chevy. I remember looking at a beautiful 1956 GMC here in Richmond Va and his cross member didn't look anything like mine. Of course he had the axel on the front with somekind of extra coil sping arrangement on the ends of his front axel where the king pins were. As for a 270 or a 302 I think if I were to take out the 235, which runs like a clock just needs seals, I'd have to find me a small block, maybe an old 283, I loved those things back in the 70's.
