Help vacuum pick up converting to power brakes

You should be able to find a brass nipple or elbow with the male NPT threads on one end and a hose barb on the other end for the brake hose. I'd drill/tap the side of said fitting for a small 1/8-NPT hose barb. You also may get lucky and find an elbow or nipple that already has a large & small nipple integral to it.

Or splice this into your brake hose once you get it hooked up properly: https://www.summitracing.com/parts/rnb-47345/overview/