You can run Lucas (non sealed beams) or Lucas PL's... Both will accept halogen bulbs and retain an authentic appearance. The new H4 units have a flat face, and IMHO, look completely wrong. If you keep a limit of 60 watts on the high beams you won't need a relay, but you might want to consider changing to an alternator on a Mk1/Mk1a. I have Lucas LR6 driving lamps with 100 watt bulbs, so I do run a relay (Lucas 6RA) and I have uprated the alternator on my MK2 to a 90 amp unit... I'm just running normal sealed beams for main and low beams. I hardly ever drive the car at night!
The wiring for the relay is simple. Terminal C1 would be the terminal for the driving lights and a tell tale (dash indicator), C2 would be connected to the blue/red wire from the high beam switch. As it's against the law in the US to use driving lights with high beams the trigger to C2 MUST be the blue/red low beam feed. W2 would be the ground trigger. This would connect to a dash switch that is routed to ground. That way the switch does not carry the amp draw, only the relay. W1 would be connected to the fuse box on either the purple or the green wire set (fused side).