[Stocker]

As I understand it, the stock wiring and the contacts in the headlight switch are somewhat marginal, aside from being decades old. Pretty sure the only time they'll give you trouble is if you put in high-wattage bulbs, which naturally draw a lot more current. Your new Sylvanias are close to stock wattage, so no worries. After the relay mod, the only current they need to carry is a minimal amount to operate the small relay.