Don't be discouraged from pursuing a sim instructor job. Flight Safety and Simuflite (and others) frequently hire pilots with no experience in type to teach their classes. I was once offered a Lear instructor position, and at the time I had no lear experience. I'd never even sat in one. The firm making the offer was nonplussed. Later, when flying a lear, my employer sent two captains to recurrent. They came back commenting that their instructor had never flown lears.
I got a kick out of a newly minted captain who came back from flight safety. He told me about what he'd seen in the sim, and how the airplane was uncontrollable without the yaw damper engaged. He told me how exceeding Mmo caused violent aileron actions, and all sorts of other sim myths. One of his first approaches in actual to minimums, he kept saying, "Wow! This is just like in the sim!" He was a classic, but imagine the folks who never did anything but fly the sim.
The problem with larger types is that there are a lot of people out of work with considerable experience in type, and they are more than content to draw a paycheck teaching in the sim. That puts you at the bottom of the list, if you've got a fresh type and no experience. More than experience in type, experience in general is useful. It's not a big deal to take someone who has similiar experience, but it would be a bit of a leap to come from a fresh commercial pilot to teaching line pilots in a heavy airplane.
Bear in mind that specific type experience isn't always necessary, and holding a type rating for the airplane isn't important. There are more than a few instructors out there who are ground instructors, and don't hold a type, or don't have experieince in type.
If you get hired into a specific airplane, you'll learn it and teach it to their standards, and will get typed as part of their program. I certainly wouldn't go pay for a type rating in the hope of getting hired into a sim instructor position.
If you desire to go that route, you will find that you can begin teaching one type, and bid into other positions as they come open...getting some book experience with various types of airplanes over an extended period of time. This isn't really practical as far as jumping into those airplanes on the line...but you'll come out with plenty of systems understanding and theoretical knowledge.
On the other hand, the entry level pay for teaching in a type program is decent. As I recall, the entry level pay for the lear position was something like fifty thousand, just to teach, with office hours and regular days off. That's not bad. They did want practical flight and line experience for that position, but none in type.
I guess what all of that boils down to is don't be discouraged from at least trying. If you feel it's something you want to do, get some resume's out, get some app forms and fill them out, and pursue it. You never know what opportunities might arise.
