Why don't you call Ruger? Technicians at the Prescott, AZ plant are experts in these matters. If it is a drop in conversion they will tell you the truth and order the parts for you. Calling Prescott is lot simpler than going through all of this guessing.
Sturm, Ruger & Co., Inc.
Customer Service Department
200 Ruger Road
Prescott, AZ 86301
Telephone: 928-541-8892 / Fax: 928-541-8835
(Monday through Friday 8:00am - 5:00pm MST)