I see no reason that you could not use them overhead as you planned. That is far different from placing them less than two feet from the birds' eyes where they cannot escape the bright light. I'm happy to hear that you will read the information on the lighting site and report back to us. There is a lot of information there. It seems that it takes them awhile to learn how to fertilize their eggs.
Many parrots have several clutches of infertile eggs before they figure it out.
Most of us have experienced the disappointment of clear eggs but eventually, the birds do get it right. That is quite remarkable considering the fact that they do not have the opportunity that their wild counterparts do of observing and learning from the older pairs in a flock. Best of luck with your birds. I will post my findings.