I don't know "which" Holleys come like that now, but all of the Quick Fuel carburetors come with adjustable air bleeds on top, adjustable IFRs on the metering blocks and also adjustable power valve restrictors. Plus they are pretty affordable. Although I've had my metering blocks off several times, my dumbass has failed to see if the emulsion holes are tapped. I'm assuming I wouldda noticed, so I'm gonna say no. But with all the "other" already being done, that would be a small job to handle. Hope that helped answer some of your question.