As with any 125 you will need to respring both forks and shock for 195lbs.
I'm riding an '00 and lighter than you are, but I need a spring job and re-valve. I feel you can get what you want out of both the 43 and the 48 mm's with the right tuner helping you.
If you are starting out MX, then you may want to just play with the clickers until you get comfortable with the bike. Once you start gaining speed and ability you will see just where you need to go. Your input at that point will be of great value to your tuner.
The 125sx is such a fun bike!