using a 64-5 LA intake on a 66 and up LA motor

I'm working on a 318 and want to use a D-64 dual plane, dual quad Edelbrock manifold on it. opening up and changing the angle on the bolt holes is pretty straight forward (and doesn't have to be super precise), but I don't want to grind down the surface where the intake bolt heads seat. I'd rather make some washers that are tapered to correct the angle on the manifold surface. I read that the correction is 16 degrees. Can anyone confirm this? Has anyone done this before? Once I get the angle confirmed is there anybody that wants to make a set of these washers to sell to me?