"I was told to rebuild the motor it would not hold up to high speeds 65 70 mph . . . "
With standard equipment in your one-ton, the engine would be turning about 3,645 RPM at 65 MPH (3,925 RPM at 70 MPH).
That would even strain a carefully rebuilt 1954 235 engine.
Before you rebuild your motor, have you checked the oil pressure and the compression?
If you plan on driving it at 65-70 MPH, will you be changing the transmission/rear-end?
