Do you have Euro lights ?
Being in Belgium, you propably do, so all you have to do is get NARVA 48884 60/55 halogens , They have the P45T base that your original R2 45/40 Bilux have , so they drop right in. No wiring changes needed . Very substantial upgrade for short $$$.
If by chance you have the 7" sealed beams, you can convert to Halogens with a kit from Hella,Chibbe , or Bosch, that comes w'7" lens and H4 replaceable lamps. The Euros are better.