You just bought a mini T- bucket with a 1967 1600 engine the problem is you can only get 55 mph out of it Could it have a Governor on it?
A car made in 1967 is now 40, that is forty years old. There are doubts it is in good working order, plus the car may have not been designed to go faster than 55MPH either way. Please check the chassis design if it is compaticle with speeds above 55MPH in order not to kill yourself before you do any speed upgrades. Ruining a classic car would be bad too.