Interesting, thanks Dom!

I realize there are differences of opinion among tuners, but I'd have to open the secondaries into their t-slots to get enough air and most everything I've read/chatted with say not to do that (as the secondary slots are further up the bores).

I thought the blades came that way, not drilled by builder. The holes are not for leaning it out per se, but to pass sufficient idle air for the idle speed. This cam has lots of overlap and needs a surprising (to me) amount of air for its 1200 rpm idle. What is your carb & combo? I seem to recall you having an even bigger cam (276@.050)?

You've said that is OK to do, but won't that cause even more tuning difficulties by introducing yet another source of fuel?

Edited to add: these plates come that way from Holley/QF. The ones I'm not using (with 1/8" holes) are stamped "325" which is factory-made.