I had a set of Carello H4 hi/lo and H1 hi beams in my 1971 (they're in storage now). No problems with low beams using the stock and replacement Hella H4bulbs (60/55W), but I could not run high beams without popping the headlight switch circuit breaker. Relays took care of that problem. However at idle highs drew too much power and the ammeter showed discharge with the original alternator.
Fantastic lights with excellent patterns. There were no 'blue' or other specialty H4s available back then, only higher power units but that was not necessary given the quality of the lights' output. Besides which the higher watt bulbs back then would have stuck out like a sore thumb and guaranteed a ticket.