I'm building up a single speed with a steel colnago master light.
I have never ridden a single speed or a fixie and would like some gearing advice.
I have a campy crankset 53/39 and was either going to:

A) use the 39 in the front or
B) go to a 42 in the front.

My concern is gearing in the back. What would be recommended for rolling to hilly roads of upstate NY.
I was thinking 39/17. It would be hard on steep climbs but manageable on the long sustained climbs of 5-7%. I climb OK and want to use it to make me stronger. 5'9'' 155lbs.

I have a set of Mavic OP that I would like to convert to a singlespeed. Any recommendations or suggestions would be appreciated.

Thanks.