At any power level, a PWM regulator is more of an intermediate than beginner level project. What is your skill set for assembly and troubleshooting, access to power components, etc? Also, what is your location? No judgement here, just trying to determine the right level of response.
Also, is 65-75 V the actual range a regulator needs to adjust to, or are you saying anything within that range is ok and the output voltage can wander around under load as long as it stays within bounds?
ak