Uhm... do you have a rear derailleur that can handle a 42 tooth rear cog? It's not even a question of having to use a very small chainring with it... I doubt the pulleys will clear the cog. I had an old MTB wheel with a 34T cog and my long cage derailer barely cleared it.

Also, no way you're gonna be able to shift on and off that thing. Hard to space it right, and wrong tooth profile.