I will be facing this situation when I get my '87 Fuso up and running. 50-42 crankset with a 6-spd cassette that appears to go no higher than 21. While I can get my fixie up Monte Sano with its 42-15 gearing, it's not as enjoyable as it sounds.

I have no problems with swapping in an 8-spd cassette and/or changing the chainrings up front if I need it.