Not really sure where to begin with your question.

If you have a modern converted 12V system it should not be as bad as you stated even with the old style sealbeam bulbs. Before you start ungrading the parts I would suggest that you diagnose the problems first. The most common reason for dim lights is one (or more) poor grounds. Take a 12 gauge jumper wire and run it directly from the negative (ground) battery post to the grounded terminal of the headlight bulb. If the bulb then burns brighter, you have identified your first problem. The headlight relay you speak about is located "inside" most modern headlight switches. Relays are used when you have a heavy draw accessory and need to turn it on-off with a light duty switch. The modern headlights with the "twist-in" bulbs are much better than even the halogen sealed beams. They are not hard to update and are available from many vintage sources.

The headlight bulbs get dim because the electricity is trying to find the path of least resistance and that is usually through some other accessory, like a tailight bulb for example.

Good luck, LET THERE BE LIGHT! LOL