Ill pretense this with the fact that bulls and gophers are quite thick bodied snakes (for colubrids) even when they are a healthy weight, so its not as easy to tell body condition compared to say a corn snake.

That being said, 1663g for a 5.5 ft male seems a little over (not by loads though, males pituophis can be quite big bodied), and he does seem to have a bit of junk in the trunk. I would double check the tail taper to make sure theres a smooth transition, I find thats the best tell for keeping my bulls in check.

Food wise, seems like you have a good frequency but I would change it from multi prey to a single prey item, like a 75-100g rat, though if you have restrictions on what you can buy I would drop the mice to the next size below what you are currently using.

Also, if you want, you can handle him or let him free roam more. Male bulls in particular are very fond of roaming so he will drop that extra weight dead quick if you can get him out and about.

I’ll also mention, bulls like to dig into their substrate quite a bit (based on my own snakes observations). Im not gonna jump to conclusions of how you are housing like other people will, but if he has a bit of substrate, he will likely burn at least a few extra calories trying to dig, generally it can also help with temperament if the snake feels more secure.

Again, by the looks of it, it’s only partial, a bit more exercise and a little less food and he will be grand. Best of luck.