Like the other poster above me, I was told that there are no stock sizes. I didn't really understand that, however, since even bespoke tailors work with block patterns. But FWIW, that's what I was told.
Crowdsourcing MTM measurements seems like a really bad idea to me, especially if you're getting that info from non-experts. I don't know if he would be up for it, but you might want to try PM'ing @mrchariybrown and seeing if you can privately pay him to generate numbers. Maybe he would do it for a small fee.