Help find street demon part

I have a very unique situation with my Holly Street demons... Running two of them at once is near unheard of. There's one old hot rod article when they first came out about 12 or 13 years ago where they put two on a Ford engine. The guy did some special deal where he drilled 9/16 holes in the secondaries...
Anyways I called the Holly tech line asking about a couple of those because I didn't want to drill holes in mine and be stuck. They gladly sent me a couple sets for free... So I could give it a try and I did and it worked and now I have four extra rear flap doors. .