800 miles? Awesome! I think around 65 gear inches is a good starting point. Just easy enough to make it up most hills without spinning your legs off going down. I think there was a discussionin the long-distance forum about gearing for long distane fg riding, and everyones average came out to be around 65". Your 46 tooth chainring paired with a 19 or 18 tooth cog would be ideal IMHO.

What kind of bike and gear are you gonna use?