I have the H4 upgrade kit that rockauto sells (round lights for an '81) and I was impressed at the improvement.
I was also reading on 4crawler that the factory harness can have a volt or two drop to the headlights, running thicker wires to the headlights can give a dramatic light output improvement. I need to measure mine and maybe try that out.
EDIT: My headlights are RAMPAGE 5089925, found the invoice but Rockauto doesn't carry them anymore.