[TButtrick]

Bad alignment won't cause vibration. Focus on the rotor/wheel/tire. Take the wheel off and zero a gauge on one of the pins. Rotate to the next pin and check for delta change from zero pin. Check both wheels. If OK, check run-out and roundness of the rotor. If OK, mount the wheels and check run-out and roundness on the rim with the gauge. If OK, check for run-out and roundness on the tire. Poor bumpsteer will also amplify vibration. If all checks out OK then suspect balance.

If I remember correctly, SPFs use Vintage Wheels? They're a very good quality wheel. Perhaps not so good quality rotors? What spindle and rotor does SPF use?