Changing Lighting During Flowering.

Good afternoon GC...

I am thinking of changing the lighting in my grow room...A couple quick questions.

Growing Chocolope DNA strand under (3) 2 tube 48" T12 Flouro lights....One is placed horizontally beside the plant to get the lower section my lady lit.

Day 61 of Flowering...about 3-4 weeks left until harvest.

I am going to replace the 2 2 tube T12's with a 150 Watt HPS (Sun Systems) on top of the plant and place all 3 2 tube Flourescents on the sides of the plant.

1. Is that advisable?
2. What was your experience when you changed?
3. Any other thoughts?

Thanks...