It is definitely worth adding a scope to your Winchester 30-30 for several reasons:
1) A riflescope will make any rifle more accurate, even a short range rifle such as your 30-30.
2) A riflescope allows you to see your target more clearly and you will be a safer shooter because of it.
3) A riflescope requires you only to place a crosshair on your target - there is no front and rear sight to line up. Despite what some may claim, when set at low power, a riflescope is one of the fastest sights you can use.
4) As they age, most shooters have trouble seeing the front sight and rear sight simultaneously. This problem is eliminated by a riflescope.
You can put any riflescope you want on your Winchester, but a compact, low-mid power variable would be in keeping with its short range, easy handling nature. Here are a couple of suggestions:
Nikon Monarch UCC 2-7x32, http://www.opticsplanet.com/nikon-rifle ... -7x32.html
Leupold 2-7 Compact, http://www.opticsplanet.com/leupold-var ... ticle.html