Check out my 235 link and you can see how I used a regular valve cover cap, drilled for a brass fitting ...
Keeps everything clean and free of leaks!
Some of the FLAPS sell push in valve cover caps with a 3/8 hose connector that can be connected to the carb air filter with a hose.
They fit into a grommet that goes into the existing valve cover opening.
At sustained high rpm there can be leaks at the grommet though.
