Use the 42. If you use the 53 you will probably pop your eyes out on the first hill you attack, to say nothing of the difficulty getting going in the first place.
The 16 rear is a good all around gear of 71 gear inches on a 700cm bike. The 18, in my view is to easy. But maybe if you are just starting out it would be a good place to begin. Just definately leave off the 53 front ring for your next Bonnevile Salt Flat high speed Record Attempt.

Fixedgearhead