yeah unless your mike tyson it gives you time to get more ameture experience and you can get more fights in like rigondeuax who had close 400 fights granted you probably won't have that many and they couldn't go pro but you can improve
I have a few questions about this... You say you used to fight near light-heavyweight. Now you've gotten fat. You're 6'4. It seems like your frame is probably small. You're more inclined to be a Nathan Cleverly than a Mike Tyson body type, right? I know this is radical and everything and nobody will agree with such a complicated plan as the one I'm about to propose, but...why not lose the weight? I mean you can't even bench a welterweight, and you want to fight heavyweights??? Drop down to 178, or at least 201. Have some fights, learn the trade, then turn pro at 175. You're not even strong enough to fight there yet, imo. Lose the weight, lift weights. Lose weight slowly, lift weights smart. Worry about heavyweight when you can bench at least 200, if not waaaayyyy more.
Just go the boxing gym and follow the workouts your coach lays out for. Your goal outside of the gym is to make you eat well enough to support your workouts and to recover from them. If you're still a heavyweight, fight there. If you're not, fight at the lower class - which is better as long as you aren't weight-drained. Who cares what your bench press is? It's a worthless exercise for boxers. It's only necessary if you're a competitive powerlifter.