As for wiring - a standard 60W main beam will draw 5 Amps (well a little over allowing for volt drop). If you’re having a loom made, just ask them to ensure the lighting cable is to the standard used in the later cars that used H4 lamps.
The relays are there to protect the switch that is right in the edge if it’s design load and once is a little old and crusty doesn’t perform well. Hovered with new wiring, new lamps and a new switch you should be fine for a few years.
Speak to someone like Wired by Wilson on here and see what he could offer in terms of a loom
Edited by GraemeC, 04 July 2018 - 07:42 AM.