You could either take it to a gunsmith or put it on yourself. I had a Ruger 10/22 and I think it had a scope rail for mounting. Should be just a matter of tightening it onto the rail and sighting it in.
Contact Ruger
100-200
175 USD
250-550 USD
175 USD
10-400 USD or so
50-600 USD or so
Naturally.
You will have to contact Ruger
You can get a manual for free by going to Ruger's web site and requesting it.
50-250 USD or so
iv'e shot plenty 22 pistols and none of them had anywhere to put a scope on it unless u welded it or something