I don't know about the leaded gasoline question--it wasn't leaded that we used and it ran just fine.There has been almost no work done on that engine. It does take 12 quarts of 30 weight non-detergent oil and the radiator is filled mostly with anti-freeze. No synchromesh transmission either.
The speedometer is actually reading 0 mph as we were standing still. As the Casey starts moving, that dial moves to the left giving a somewhat erratic speed reading and it would have to go completely around to hit the 75 reading. When I rode it some years back from the Durango roundhouse to a couple of miles above Tacoma, we made a top speed of about 25 mph through the Animas Valley. It is noisy--straight pipes, and rides very rough. The front passenger compartment is very small and the doors too narrow and nothing to grab onto getting in or out. But a ton of fun to ride regardless.
fritz