I'm working on a Phenix PH011 .55 Powered Corsair. The Manufacturer (Phoenix) says to mount the engine at about 120 Degrees Counter Clockwise from Vertical so the Muffler is at the bottom. Phoenix suggests and designed the Fuel Tank be mounted on a flat piece of lite plywood above the height of the Carburetor for the typically installed Inverted Engine. It's at least 1.25 Inches above the Spray Bar of the Semi-Inverted Carburetor. So this is going to cause problems when I have the tank full and I'm waiting to fly because the fuel will syphon out of the Spray Bar. I thought I would cut out the original Tank Floor, Cut the Mid Horizontal sections of two Fuselage Formers, and lower the Tank about 1.25 Inches on top of the remaining portions of the two Fuselage Formers. The Tank would also need to move backward from the Firewall about 2.5 Inches because the tapered Muffler Cavity was built into the lower portion of the Fuselage. I don't think the extra 2.5 Inches should hurt the Fuel Flow while using Muffler Pressure with the two-line Tank Set-up. Let me know if anyone thinks I'm wrong. I'll include an Illustration showing where the existing Fuel Tank Floor is and the Former Horizontal Sections I intend to cut out.

I'm contemplating moving the Phoenix Placed Fuel Tank Floor so it fits on top of the lower two Formers you see in this illustration. I need to move the tank rearward about 2.5" because the Muffler Box is below the Forward portion of the existing Fuel Tank Floor. So the rear of the tank will be about even with the forward edge of the Gray Wing Joiner Tube shown in the photo.