Modern Drivetrain Swap into '65 Valiant

Does the governor instead also somehow work in relation to car speed?
The governor has NO IDEA about engine rpm;
The governor has no idea about the roadspeed;
The governor only knows driveshaft rpm, and only responds to increasing rpm , by increasing it's Shift-Command Pressure.

Anytime a rear gear ratio is changed, the governor will need to be re-educated. And the Speed-O will need a new drive-gear.