Lifters oil restrictors?

If I restrict my
Oil I do it under the rocker shaft so if I want to go bigger or smaller it’s easy. I got the brass set screws on eBay but my buddy used stainless steel on his 440-1 heads over the weekend and they drill easily.

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That's a great way to do it. Much easier than installing it in the block like I've seen too. What size orifice do you use?