Your time would be competitive today. For a long time, the APC 6.5x5.0 was the fastest prop, but then we discovered the newest series of the Master Airscrew 7x5 (non-scimitar) was about 0.4 sec faster. Prop mods are allowed. More, less, or no head shims are allowed. It sounds like you either need to move your tank outboard or build a wider tank. Your tank IS uniflow, isn't it? Moving the tank outboard would lean the engine, requiring a richer needle setting on the ground. This would get more fuel into the engine for "wetter" pits. Start by simply putting a 1/4" spacer between the tank and fuse and seeing how it goes. (Loading the engine with more prop will also necessitate a richer ground setting.)
Bill Bischoff