The 905 uses a ‘29 Quad flywheel. A Speedster flywheel is a different size crankshaft and will not work. The high speed versions of the Speedster, ‘28 Quad and ‘29 Quad were made with flywheels having seven degrees more advance. The 905 Special Speedster will benefit from using a ‘29 Quad high speed flywheel. But…lots of luck finding one. I ha
ve been looking for some time with no luck

Fred