If you have power on both high and low beam wires on the engine side of the firewall, then the problem HAS to be in the engine bay harness, grounding, sockets, or "it's possible" that the high beam filaments in both lamps are burned out.
I bought a '73 Satellite back in the '80s. I'd hit the high beam switch and no high beams. I thought, dang- bad switch. Nope, it was both high beams burned out.