If you are just getting started get G.P. Blair's book, Design and Simulation of Two-Stroke Engines get it from SAE International ~$100 (amazon wants a lot more) Get the software along with it. I have heard TRS software is similar, but GP Blair's is cheaper plus it comes with a book explaining all of the engineering behind it.
I have paid for some port jobs in the past from a very well known atv builder/supplier that performed as well as stock, you could hardly do worse, go for it, get good at it, then you too can have your name etched in the side of bike motors running all around the country.
B