Here is a couple of pics of a catalog like the one I was referring to. The first page is the ipl., and the rest of the pages give the specific part number for each model carb..
I tried now, but L screw is not fit into the place of H screw. It looks like that thread of H screw is different than thread of L screw. I measured the hole of H screw, it is around 28-30 mm.
You might contact the guy selling this catalog, and ask him if it has a selection for the HL146. The book might be worth it for the part number, and see what other carbs used the same screw.