Moving from Competitive Masters Running to Swimming

Hi, I am in my early 50s have run competitively most of my life. I started swimming when I was 3 years old, but never learned freestyle. Nevertheless, I feel comfortable in the water. For the past few years, my training consisted of an hour of running (7 min/mile easy pace 4 times a week, 8.5 min/mile threshold twice a week.) After my third injury in 18 months (hip labrum tears and a sport hernia) my sports doctor said that I need to drop running and take up swimming. I bought the book "Swim Smooth" and after a 2 -3 weeks learned the basics of freestyle lap swimming. My question is how to best move from where I am now (this month I am working on mastering a the 6-5-6 drill and doing more efficient flip turns) to 60 minutes X 6 days a week of freestyle swimming. Does any one have any suggestions?