This is a training subforum question.
But the answer is still yes, you're way too late. You can do some amateur bouts against similarly aged and inexperienced grandpas like yourself, but you are way, way too old to go pro. You'd need two years of training to not completely gas in the first round and it sounds like you've avoided cardio all your life in favor of bulking up which exacerbates the cardio issue. Throw in the fact that you've literally never trained in any martial art before and I'm doubting if this is even a real post. Everyone should get in the cage at some point in their life just for the experience but not as an old man that doesn't know what he's doing.
Do yourself a favor TS. Look up Mike Tyson's training regimen. If you can do that, sure, get a fight lined up. If you're not ready (or physically capable) to spend 3-4 hours a day training plus intense cardio to the tune of 5-8 miles running daily or every other day, you have no business stepping into any kind of sanctioned fight.
My advice to you would be stop doing whatever weight training you're doing and do something useful like getting into a boxing gym, judo or BJJ school. Lifting weights and shit is a waste of time if all you're doing is jerking off to how good you look. You'd still get your ass handed to you in a fight. It takes years, YEARS of training at a pro level to be able to go full rounds. Every douche bro you see at the gym probably has two minutes tops of emergency energy before they completely gas out. That's what happens when you spend your time lifting weights instead of punching or throwing people. The other factor that never occurs to noobs is that whatever cardio you do have is going to be sapped every time you get hit. That's why most street fights end with a couple of dudes ready to throw up on each other after a minute.
