I need to replace the old rusty heater hose barb on the front of an Edelbrock #7521 air gap manifold. I know the heater hose end is for a 5/8” heater hose, but what is the size and thread pitch for the threaded end? I plan to replace the rusty 90-degree end and the brass insert into the manifold that are there now with a stainless straight or 45-degree barb so it looks better and cleaner. Or maybe I need to keep the brass insert there and just thread the stainless barb into it? Any help is appreciated on which barb/fitting size I need and whether I need to keep the brass insert with a stainless barb/fitting. Thanks!