Sorry, I was in a hurry when I replied to your post and I mistakenly added your payload and fuel to the maximum zero fuel weight instead of the empty weight. By the way, the empty weight should be 97,650 lbs, not the number you mentioned.

The climb charts for a 727-100 at 160,000 lbs take-off weight show 19 minutes, so it looks like your climb, and the flight model was pretty accurate.

I don't think Captain Sim relies on anyone to tweak their flight models and I can't speak to how they develop them or what their goals are in that respect.  I do note, however, that they designed a sort of generic flight model to represent several different aircraft variants, so there is no way they can have real world numbers with that approach to the product.

Anyhow, I built my own flight model in an attempt to model one varient of the 727-200 that interests me and for which I have the necessary data.