You have to re-machine the pushrod holes, they will cut through the gasket face. Some clearancing may also be required of the manifold. The W2 AB heads had this.
The 48 degree Indy heads have additional material on the gasket face and the different pushrod holes.
It might be best to sell the Edelbrocks now, and upgrade, as it might be harder to sell them once you have modded them for the 48 degree block.

I am sure Ryan will chime in with more info.