older 350 into new Blazer

We have a rebuilt 350 from a 1975 impala and we are putting it into a 1989 Blazer. We planned on using the intake manifold from the Blazer engine but the intake manifold from the Blazer engine has a different bolt angle on the center bolts. Does anyone know if that can be corrected by redrilling the manifold, or, does anyone know where we can purchase a manifold to fit the old block but with all of the new ports and connections to fit the 89 Blazer.