The mates on my ship keep my immersion suit in tip top shape & it can pass USCG/PSC easily. But the immersion suits in all the schools I’ve been to have been ragged out beyond repair. If you can’t find a real suit big enough for you perhaps you can buy 2 old used ones & get a custom one made from the material? Most medium to large size cities still have alteration shops with seamstresses & tailors to do that kind of stuff. As long as it has a half legible USCG print on it, a zipper that works & doesn’t bust at the seams while putting it on in the water it would probably be better than most suits offered from a school.
I wanted to close out this thread with some info that may help other folks in a similar situation. As it turns out, no standard made suit from any of the major makers would fit me in the chest area. Currently, no major maker will provide a custom made immersion suit due to a shortage of material. All material is being used for standard sized suits.
I did find a new maker of a very unique immersion suit, one that meets the new Polar Code along with USCG, MED, SOLAS, etc. If you suffer from claustrophobia this is a winner. The suit is made by White Glacier Immersion Suits in Puerto Rico. This company has been making bio-hazard and chem warfare suits for the USGov for some time and a few years ago got into survival suits. This suit won’t waterlog like neoprene and keeps you dry and warm in extreme cold conditions. It is a bit higher priced than other suits but provides superior protection in extreme situations.