For a quick and dirty sim method I use http://www.thrustcurve.org/
It only uses your rockets raw data: weight, diameter, motor mount, and Cd to calculate sims for every
motor on their website (pretty much all current rocket motors available) that will fit in your rocket. Sims are calibrated based on the rockets dry weight (no motor) with each motors loaded weight being taken into account for the sims.
The outputs can be downloaded in excel format and printed off to take with you on launch day. Its good to know where your Cp is to know whether your rocket will be stable with the chosen motor however.
If you have an altimeter you can calibrate the sims based on the altimeters data to work out a more precise Cd, I find this isn't really needed though; most rockets are between 0.5-0.6 with 3 fins and near 0.75 for 4 finned rockets.
This is what I use for every rocket as it provides a lot of quick easy data, and the sims are really pretty accurate; for most 3000ft flights they are within 200-300ft.
PS I've got a stealth junior too, easily my favourite rocket, its last flight was on a H268R and that was a spectacular flight. I think the best motor for it is a G77R-M though - the reload.