Couple of thoughts:
1) Your report was at the zip code level. We often recommend using the "start MAPS" option to be sure that the receive marker is right over your location in order to get the best picture of terrain effects. However, in your case, you are probably OK.
2) With that kind of report, you should be able to use an indoor antenna, like the Terk HDTVi.
3) Check out
this forum. There will be a reception results thread for your area.
4) You need very little gain, really. The RCA 751, aimed southeast, should work OK. Do check out the other thread first, though.
Good luck!