You can try all sorts of band aids such as those that have been described here already, but you will wind up causing problems for yourself and will not get a meaningful improvement in light output. One of the important reasons for this is not the higher output bulbs, which are important in the correct installation, but the properly focused glass lenses (some 124s have plastic lenses, another good reason not to use high wattage bulbs) that put the light where you can use it. Wait a little longer and buy the euros. You can sometimes score a deal on ebay and through Hemmings, so keep your eyes open. I have flat glass Bosch euros in my euro 500SEL, and upgraded to 85/100 bulbs with no problem whatsoever from police. Since my car is a euro it has the vacuum control that allows me to lower my lamps to compensate for a car full of people, etc. (a very cool thing to add to your euro lamp install, cheap too) and with all the HID headlights around these days euros don't stand out like they used to. Get the real thing and you'll be glad you did.
'76 Moto Guzzi 850 Le Mans