It's probably throttle-body injection. 71hp, 2700 lbs, I had an old Datsun with similar specs, I bet it can do 80 if it's geared right, given no headwind and a long enough flat stretch.
As far as safety, it looks to be ca. 1980 suspension and DOT tires, it should handle OK if you don't get too wild. I bet they drive these highway speed in China. The issue is probably crash protection and emissions. Just don't crash at speed.
I'd look for the speed sensor (probably near the tranny output) and unplug it. You'll lose your speedo (if it has one) but I bet it will go then. Use a GPS for speed, it's more accurate anyway ...