swap intake manifold.

I have a 1989 K2500 with 5.7 ltr which uses a throttle body. the motor slung a rod. I have a rebuilt 1974 350 that I want to put in it. I was told that the intake manifold from newer motor will not bolt onto the older motor unless I wobble out the bolt holes because one screws down and one at an angle. I want to swap the manifold in order to use throttle body. Does anyone have any suggestions or ideas