Dave, VHF, UHF, or both? It'll be easier to point you to the active machines once we know what bands you will be using. Also, here is the website for the Oklahoma Repeater Society, the state coordinating group:
http://www.qsl.net/orsi/ Never mind the out of date notice on the webpage, the database itself is reasonably up to date. We are in the process of purging the "paper" repeaters, and getting the tones for the open machines listed.
Also, there are nets on various nights, on various machines. Have any idea what days of the week you'll be in the area?
Oh, BTW, you'll be able to hit most of the Okla. City machines from Moore, so look at those listings.
Moore is also the meeting place for twisters before they head out on their spring tour, so you'll want to make a note of this repeater 145.410 MHz -600, PL 141.3, sponsored by the Oklahoma Department of Civil Emergency Management. This is the anchor repeater for a linked repeater system used by the Norman Forcast Office of the National Weather Service.
Mark S.