That is a very mild cam, I really find it very interesting that you had to drill the throttle plates to get the idle AF ratio right. You really should not have to drill holes in a Holley carb that is on a very mild engine build. Holley must be doing something strange these days. I never saw that back when I was really into this in the mid-80's through the early 2000's.
Yeah this subject has been hashed and bashed on here for a long time now.
I don't believe it is to do with the cam at all, but the Holley Street Avenger 670 carb that is known to be rich out of the box. The guy who did my carb set-up is a locally well known tuner who works largely on race cars (Mud puddle stock cars I call 'em).
What ever the reason, this worked. I no longer have excessive gas smell or raw fuel dripping out my tail pipes. It allowed the transfer slot to be set square where they ought to be. Before that, the primary plate needed to be cracked open beyond that just to get it to idle, therefore needing more air.
This combination works for this engine and that's all the matter to me. It idles well and pulls like a train.