Where to place smoke fitting on RV-14A firewall?

I am looking for the best location for the smoke fitting on the RV-14A firewall. The engine mount is ready to go on and it will be easier to locate the fitting now. I am thinking centerline is best. Too low and it will conflict with the fuel line fitting and too high and it may conflict with the engine mount and nose wheel assembly. Does anyone have a location and/or picture for placement?

Fitting

What is a smoke fitting?

Allan
Cape Coral
RV 14A ready to fly

Van's refers to a similar fitting as a fluid fitting on page 31-11 figure 3. The fitting I am trying to position is taking the smoke oil across the firewall.