No, you don't need to modify anything to the headlight unit.The back cover will only be a bit tighter since the connector side of the new bulb is a fraction longer than the original bulb. But you still can get the cover watertight closed without excessive screw force or braking the cover.
You may want to look for a duo-pack of these bulbs: cheaper per piece and you have spare one. For example:
OSRAM Night Racer 110 Halogeenlamp H4 60/55 W.
It's not so obvious from that page but it is really a
pair of bulbs.
Paul