Recently adopted senior leo, considerations?

We just adopted a 10ish year-old leo and it unfortunately seems like he wasn't getting great care. My biggest concern is that he wasn't receiving supplementation of any kind and obviously didn't have a UVB lamp.

We planned to transition him to a bioactive 40B set-up but I just wanted to check with the community to see if there are specific steps we need to take before/during the transition with him. His body condition looks great, he might even been a smidge overweight!

Any advice or reassurance is welcome!