I really like the idea cuz you can increase yield per squaremeter for sure by 100% and more by going into vertical orientation. I've seen lots of vertical grows but with 2 600w HPS bulbs inside a vertical hanging cooltube and the plants arranged around the bulbs. So exactly the opposide way.
With an outer diameter of +56" you better use HLG-600's or two HLG-320's. You can also use 8 bars but the PLC strips are only available in 2ft and cover only 4ft. But thats not really a problem with more bars cuz you could alternately leave on top and bottom about 1ft of space on each bar because they turn aound anyway. A bit less intensity in this areas but you would still have 5ft usable height.