For the W123, you also have the option of getting round E-code lights, which are tremendously better than the sealed beams. They don't look as cool but the cost is only ~$100. If you don't need fogs, you can add additional high beams like Jaime did (see link below). If you can get 123 Depo/TCY lights cheap enough though, that would look really nice. (BTW, I agree with your theory!)

http://www.jaimekop.com/240D/lights/

I have the round E-codes on my 123 with "plus 50" bulbs from Dan Stern. Works great!