Back about 15 years ago I used the Magic Blue head made by Tom Muggleston on several Fox .35's whit great success! His head was hemied and had the plug angled toward the back of the engine. This configuration in my opinion was far superior to the Fox Hemi Head. Stuffer back plate with ST NVA added greatly to the performance of the Foxes when used on profile planes. Up right, and inverted mounts ran just fine stock. For what its worth that's my personal experience any way!