For the money that you are talking the Marlin in one of the model 60 variations would be great. It doesnt need any modifications and shoots great out of the box. The ruger 10/22 is nice, but is a better gun if you are wanting to modify it. A 22 will work on coyotes, but not at extended ranges. About 75 yards is tops and you may want to be ready for a quick follow up shot.