Nice work, Jouf! What a bummer it doesn't fit him. I've had that happen. The first sweater I designed from scratch, I took measurements, and didn't leave a bit of ease. It was for my nephew, who was 1 year old, and I think it would have barely fit him as a new born! LOL.
Hmmm, since it is a vest, and you don't have to worry about sleeves fitting, I'm wondering if you could insert a couple of side panels to make it fit your husband. I've never attempted anything like it, but if the neck and shoulder width fit, and it's mosly in the abdomen and belly that it needs room, then it seems like it could work. ...just a thought.
I like the idea of making a sweater for yourself out of it, too. As long as you like the color and style for yourself, you could make it gorgeous.
Thanks for sharing the picture. I hope to see what becomes of it!