A 180 will be fine. However, at our altitude, you may find it a little slow or you'll have to settle for a smaller prop to get adequate speed. My KMP ME-109 has a 180 in it and its spinning a 16x8 2 blade at 8300(motor still is not broken in). It flies well, but isnt all that fast.
If your looking for good prices on either the 180 or the 220, come up to greeley and get it from Things with Wings. This place normally sells motors of this size for at least $50-100 less then Horizon lists them for. They sell almost everything in the store for about 10-15% less then any Hobbytown, Colpar, or whathave you.
In either case, whether you put the 180 or 220, you can easily have the plane built, test flown, and ready for Warbirds over the Rockies at the end of Sept. Hope to see you there....with or without your new ME-109