72 K20 Crossmember question

[Yammerhammer]

Hello, Im a long time lurker but I dont post much. We picked up a 72K20 for me son and I to build for his first truck. What little history I know is that it was a factory auto a/c p/b p/s truck. The guy we had gotten it from to the cab, clip and bed off and cleaned, re-sprayed the chassis and put it back on with 2" body lift. He didn't connect anything back up except the steering column. He had set a 292/SM465 in, for what reason I dont know however, the 6 banger was not bolted, didnt line up with crossmember. Now my son and I plan to keep the SM465 but put in a big block. As I took out the 6banger, I realized the holes in the crossmember dont line up with the ones in the frame. The frame has three holes, each side, top and bottom. The crossmember has two holes, each, top and bottom. These two holes dont line up with any two of the three on the frame. Wrong crossmember or????