You can select vests for big guys according to the size or shape of the body, not according to the age. The vest should be comfortable enough to wear.
Types of Vests for Big Guys
Wool blend vest with fleece backing. Wool blend clothes pinpoint performance by mixing natural and synthetic fabrics to optimize function, maximize comfort and look great. This type or material of vests are midlayers warm you alone or together by reflecting and regulating body heat. Wool blend creates a lightweight barrier that is breathable, wind and water challenging and offers high mobility for better freedom of movement, delivering versatile protection for a wide range of activities year-round.
A vest alone may be fine in his case. If concerned get a 3 piece take it to a decent tailor and ask them to add some waist restraint to the jacket. This curves the waist line in a bit and provides a light effect. If you go suit just make sure the jacket fits in the shoulders as that is the most difficult if not impossible part of fit for a tailor to adjust.
Vest for a big and healthy guy
You can wear a vest which didn’t have a back. So it tied around neck and then should had an adjustable strap that went around waist. You can’t tell if he isn’t wearing the jacket, but I don’t think it looked bad either when he wasn’t wearing the jacket. He felt much more comfortable with this type of vest than with a “regular” one. Backless vests are meant to be worn with a jacket, because they aren’t as hot in the summer. They are chosen by rental companies because they are somewhat adjustable, and can fit a wider range of bodies. This means that they can carry fewer sizes, however still tend to have too few sizes, even at that. You don’t really see them much anymore, except for rented tuxedos, because men these days like to take our jackets off. The backless vest was invented in a day and age when it was unthinkable for a gentleman to remove his jacket during outside the company of intimates. There are a lot that will since they're usually one size fits all, but some plate carriers come in different sizes. The Condor vest fits to a big guy who is huge. Lots of vests are very adjustable. It is very breathable, thanks to the mesh, and you can load a ton of heavy gear on it, but it doesn't feel like you're wearing nearly as much weight as you actually are. PLUS, it's relevance to this thread is that it comes in an adjustable 4XL size. One of my team mates is about 6'2" 290 lbs and wears the 4XL and says it fits well. There are some vests which can adjust up or down 1 size or so.
Where to buy good quality Vests for big guys?
You can buy good quality vests for big guys from branded designer shop, retail stores or you can buy it online. Check the quality, durability and color before you buy or order vests for big guys. Size should be adjustable.