If it is a Winchester 94 the 'older' ones are difficult to mount a scope. The vertical ejection interferes with scope placement. There were some rigged scout type mounts that attached to the rear sight dovetail but probably not too satisfactorily. If it is the newer 'angle eject' model then scope mounting will be no problem. As for the scope itself I would get a small/compact 2-5x variable or fixed power from say 2-4x. A full size scope overpowers the handiness of a 30/30 carbine and makes them look like a scope with a rifle attached.
Another almost as good option(if not better) is to put a receiver sight on it. They are handy accurate and fast for average eyes shooting to 100yds in the woods. In good light they will allow you to aim precisely farther than the 30/30 should be used on deer. Plateau Hunter