80/100-watt H4s, 100-watt H1 bulbs. Modifications? Relays for sure, the factory lighting circuit cannot handle the current draw, approaches 30amps with all four high beams on. Also, recommend the relay to lamps wiring be upsized as noted in the diagram above. Also, ceramic plugs on the H4s, they do generate a bit of heat. No physical modifications to fit the housings in the buckets, direct replacement. Compared to sealed beam halogens? Much more light output and a more precise and defined/wide light pattern. If you are still running a non-modified factory stock original charging system with an ammeter, be sure to draw your relay/lamp power from the alternator, not from the battery directly.
Last set I bought from Summit, housings and high wattage bulb set was about $275 IIRC. Housings include the 55/60-watt H4, 55-watt H1 bulbs.