RPM at 60 is 2911.
Tire width is 10.4 inches.
Tire height is 31.6 inches.
Results Table
Speed RPM
10 mph 485
20 mph 970
30 mph 1455
40 mph 1941
50 mph 2426
60 mph 2911
70 mph 3396
80 mph 3881
90 mph 4366
100 mph 4852
If your motor is in reasonable condition it should turn toward 4,000 RPM safely so your top speed is more than 80 mph.
Assuming it has a point type ignition I would not be surprised if old points start floating around 4500 limiting your top speed. I don't know the 292 well enough to speculate on its other limitations.
RPM at Speed
