Just an update on this question. JohnBuckner's comment on tank placement is spot on. I went back and read the engine manual for what must have been the 1000th time and sure enough there is the information on page 12. If I had the cash available I would mount the engine on it's side and loose the stock muffler in favor of a Pitts style exhaust out the bottom of the cowl. But lacking the funds I'm going to press on with the inverted mounting and bring the fuel lines through the firewall as high as practical and the install a filler/fuel dot, probably on both the fuel line and the pressure line as well. The idea is that it will allow me to open up the line(s) and vent to atmosphere to break the siphon. As someone already pointed out, once that line is completely filled, it will continue to flow until the level drops even with the spray bar.

But again, thanks for the feedback. Having a fresh pair of eyes on a problem is always a good thing in my mind. Y'all take care.