Get the 450 shock and change the clevis, if your really handy you can redrill the existing clevis, its a pain but can be done, changing it is much easier. Oh and you must depressurize the shock first or you'll blow out the needle, springs and all the good parts for the rebound adjuster. anyway if you wanted the latest stuff thats what I'd do. I have not used a 450 shock but I have used the 04 05 250f shock with no issues.