For background light opinions differ, but 5000 to 6000 Kelvin is good ( I use a 6500 myself). As for CRI get the highest rating you can, I think 85 and up would be considered acceptable.
Fwiw I just got my first megaray a couple weeks ago, the beardie seems to like it just fine.
For the record, you don't need background UV - let your animal decide when they need it. Just keep your temps right so it can comfortably photo/thermometer regulate.
Regards,
Brian