If I had to guess I'd say 25% if not more of the armor threads you look at here will have some type of armor sizing modification. I will tell you this, if the entire set of armor needs to be altered, and it sound like a good majority of does, you're talking about a lot of work. Maybe even more than building a whole new set
Depending on how it was assembled if it was put together with E6000 glue then the dismantling task isn't so, bad still the assembly is still going to be a chore depending on the amount of modifications needed. If CA (or superglue) was used you run the risk of seriously damaging it upon disassembly.
I don't mean to the Debbie Downer here however, coming from someone that's been down this path on more than one occasion, yea
IMHO I would sell it, take the money and buy a new kit and build it to your body type. Perfect the first time.
Not sure this is what you wanted to here but I hope it helps.