125-200cc '99-'00+ 125 parts interchangability

I just purchased a 99 WR 125 which will be a bit of a project as it needs some TLC. So far I've amassed a list of things to replace including levers, shift lever, plastics, and seat cover. My last project like this was my 99 KTM 380 (don't hate the pumpkin!) which I converted to '07 bodywork along with powdercoated frame and swingarm. I'd like to do something similar with this bike. It appears that it may be possible to upgrade to the 04 bodywork for increased choice and availability of graphics by swapping on tank, subframe, airbox and seat. Is this correct?
How about the other things like the pegs, levers, and shift lever? I've found aftermarket parts but it's mostly listed for the newer bikes. I've searched the forums but haven't found a whole lot on the older bikes. Oh ya--I'll post some pictures soon and track the project for you guys.
Thanks!
Jason