I doubt you'll end up with a single purpose bike.
I know that sending your suspension off SOUNDS like that.
I own a 97, 99, and an 02 YZ 250. The stock fork valving is so far off that anything would be an improvement. I spent a lot of money on the forks. Subtanks, springs, etc. I never found any set-up that was decent without revalving. I believe the factory engineers were drunk when they picked the stock fork valving, or they weighed 450 lbs.
I believe the shock is liveable as it comes from the factory. The forks are not. A motocross valved fork is going to feel much better than stock in all conditions (IMHO).