Actually strength training calls for a lower rep range than muscle building. Muscle building is like 6-12 reps a set but strength building is under 6. Just make sure the exercise is appropriately difficult. Set numbers should be the same. 3 days a week is a pretty good frequency though, although once you get used to doing difficult exercises frequently you can do it more often. Meanwhile that approach may not be optimal for muscle building because your muscles need a lot of time to regrow, whereas with strength training a lot of it is neuromuscular recovery, which doesn’t take nearly as long.