Jeremy, need help with spring rates

I have a few suspension questions I need help with.

I'm 6' 200lbs and ride a '99 CR125, mostly trails, some MX, but I do like big jumps. I don't do any racing, just riding for fun. What would you reccomend for spring rates?

Also, How much of a difference would changing the springs make? For someone riding for fun, is it worth changing, or should I just ride and be happy? Would this also require a revalve?

Thank you Jeremy, I appreciate the help. Looks like I'll be getting springs soon!