Hi! Check out this video, it’s the method you describe and I did the same with my 30L to install the ML120L https://youtu.be/QXvU18k10io

He used M3 screws, here’s the link to the ones he recommended Eastbuy Water Cooling Screw -... https://www.amazon.com/dp/B088WY8G61?ref=ppx_pop_mob_ap_share

I guess you can buy similar M3 screws but make sure to watch the video, he trims them down to a certain length.