MJD,
Granted, the Perry carb could be either a large bore version or "pump" carb- the large bore carb throat diameter is .275 " while the pump version measures .370". I just miked my own carbs.
Either carb will run fine with muffler or crankcase pressure, the only difference that the idle will be compromised with crank pressure. Note that I flew the "pump" carb with tuned pipe pressure (same as muffler pressure) for many years and was able to achieve a reliable idle about 6K RPM with a good transition to high speed. Again, this engine should satisfy your Extreme Speed requirements very well.
Rgds,
Art