That's a fairly light load. something in the 10 to 14 lb range should do it.
When playing around with recoil springs, it is best to have the full range, in your case 10 to 17 lbs.
Use the spring that will work the gun reliably when holding the gun limp wristed. Many err on the side of heavier springs, but they are harder on the gun, disturb follow-up shots more than lighter springs and often do not work limp wristed.
While your at it, might as well go to a 16 lb hammer spring. Plenty stong enough, easier on the gun and a better trigger pull.