I applied at SimCom in Scottsdale for the C421 and KA90. During the phone interview, starting pay was around $42K then an increase after approx. 6 months to $48K. Bigger, faster, better aircraft = more money. Most guys on those aircraft you listed were making in the $50K+ range.
I turned down the position as you will NOT be flying real airplanes. (Maybe 5% of the time you'll fly a customers plane but it is rare according the powers that be at SimCom.) I still wanted to fly airplanes from Point A to Point B. Also told that a lot of the instructors were older, retired types who either lost their medicals or just got tired of the on the road kind of job. You'll be home every night but will put in long days. I was told from 7a to 6-7p Mo-Sa.
That said, you'll get typed in whatever you teach which after a few years you might be able to turn into a job flying the real McCoy on the street.
If I ever lose my medical or get tired of flying the real thing, that's where I'm going...
Hope that helps...if you call SimCom in Scottsdale and talk to them, they are very open and are willing to give you their time...
Eric