Get the SA, or if you want to do some "put together", get the S. All Align 450's are the same size except for the earlier XL which had a short boom I believe. The S kit is $229 from about anywhere and comes with the motor and ESC. Can't go wrong there. DO NOT put that junk from the HBK2 in the 450! You will be seriously sorry later, I promise! Go with the standard, Hitec HS 65's, LGT 2100 gyro and a Futaba digital tail servo. That's it.
Dave