Hi Jack,
You have sealed beam headlamps, good for waterproofness but not the birghtnest for seeing with!
One of the most tried and tested conversions is Wipac's crystal bowls along with a decent bulb, I find Halfords extreme brilliance bulbs are very good value for money and give a much whiter light which is best for seeing with.
The Wipac bowls are available from most of the online parts places, try Paddocks, MM4x4, LRseries etc