As others have mentioned, a little more info about how you hunt and how far you can ethically take a shot on a coyote is important (including how well that rifle that you haven't put together will shoot, i.e. is it accurate enough to be used at that range?).

Personally, I'm a high magnification type of guy. I would rather shoot at 20yrds with a 6x scope than shoot at 500yrds with a 9x scope, so I tolerate being "over scoped" at close range. I also keep a shotgun at my side most of the time while calling, or have a partner on a rifle while I run the street sweeper and the call.

A good old 3-9x glass is hard to beat for most coyote hunters that are calling and won't shoot over 200yrds. I don't use one that small, but it's hard to go wrong. I usually recommend a 50mm or larger objective, and a 30mm tube to improve light transmission, since so much of coyote hunting is done at dusk and dawn. If you plan on taking longer shots, then look at 4-16x, 6-18x, 5-20x 5.5-22x, 6-24x scopes. It's REALLY not that hard to shoot game close up in a 4x or 6x bottom end scope, but it's pretty rough to shoot a coyote at 600yrds out of a 7x top end scope.