Your revival's electrical system is powered by regulated AC power from an 80W magneto (~2/3 of which seems to be for headlight + taillight + accessory lights; power for brake light and flashers come from the battery via a rectifier):
Stock bulbs appear to be 36/36W (high/low; only one active at a time). A 35W halogen BA20D bulb would be a super easy upgrade. Halogens emit a higher percentage of their energy in the visual spectrum compared to traditional incandescent bulbs; roughly 25 lumen / watt compared to 15 lumen / watt, so they should appear about 60% brighter.
If you want to use LEDs (can be brighter for the given wattage), you'll either need to find an AC capable bulb (most are DC) or rectify the AC to DC. Your bike already has a rectifier/regulator (Tomos P/N 230844), but you'd have to rewire it to use the rectified DC output, and I can't find any specs on how much wattage that unit can provide. (edited)