This tool / screw kit works fine for the rear carb screws. You have to figure out exactly the route through the choke linkage, fuel line, vacuum lines, it fits and works both sides. Read thoroughly the instructions on the eBay page.
No need to get a ProMax setup. And you can use the stock screws for the front carb-

Edit- I'll be installing the tool before starting the engine. You can feel the ball end of the tool clip into the socket head idle screws.