I just went out and measured my old cut off Chevy dist. that I use as an engine primer, It's exactly 1.24" or basically 1 1/4". I don't have a Chevy intake here right now as I have switched over to 500 Cadillac stuff. The Cad dist. fits very snug in the int. hole. Maybe someone reading this could measure their Chevy int. dist. hole and tell the OP.
Question....is this a brand new Edelbrock intake or a used one? if used maybe the prior owner for whatever reason bored the hole out a little. I don't think just centering it and cranking down the bolt is a good idea at all, it should fit properly.