actually if you use a small T fitting it will work, how do I know, its how I fuel my H-9 P-40.
fit the small "T" bellow the pressure line fitting in the muffler, I use the cross part of the "T" for the over flow so its a strait line and the side off the T to the pressure fitting, then run the line out of the cowl.
I made a custom line holder out of alum. "L" stock,just a fuel line size hole to hold the line when plugged that I screwed into the fuse, I plug the line with a small socket head cap screw after I am done fueling.
while filling plug the muffler with your finger or a stopper and run the over flow to a catch cup to get the exess fuel that will run out, there will be about a 1/4oz of fuel that runs out as over flow.