JMC, I had the same blue 1971 H1 Mach III. Below 5800 rpm it was slower than a Honda 90 but at 5800 rpm hang on because the 60 hp hit all at one time. Harleys,, Nortons and even the 750 Honda was just left in my cloud of blue two stroke oil. It was a trick to launch the darn thing. Just lean as far forward as possible, take up to 7000 rpm and let it go. The first rear tire lasted about 1000 miles. It was the fastest bike around, that is, until Kawasaki had the gall to release the 750 Mach IV in 1972. I was no longer the fastest.
That defeat still haunts me to this day.