68 how do you keep the parking lights on with the headlights

Its a function of the HL switch. I think around mid 68 was when the law was changed. A switch from a 69-72 should work and will give you PL while HL are on. If you start playing games with wiring you will have a problem with the HL being on in both positions unless you use one heavy duty diode to keep the current from flowing to the HL side when the PL are on.