Sorry for not replying back to this thread. Been so busy with work, holiday shopping, and tearing into the Derbi...of course :D
Appreciate everyone's input. A lot of good info and things for me to take into consideration for future plans. As of now, I've decided to completely tear the bike down, replace any parts that a good evaporust soak, epoxy, and elbow grease can't fix, and rebuild in a "stock plus" configuration.
Current performance plans - and parts I have are as follows:
Keep stock 6 roller, install Dos ramp plate. Keep stock weights until tuning time begins.
New dayco belt
Removed the variator spacer / restrictor. Believe it was 5mm. Possibly 8mm. Can't remember.
MLM / metrakit pipe
43.5mm airsal with stock head. Keeping decomp. Have a good one from Dos and another from Richard as backup
Keep starter shoes for pedal starting. Upgrade clutch springs. Keep stock gearing 13/33 for the time being.
15sha (came with it) w/ new filter. Get a 15mm sha intake with upgraded reeds. Either gila or the assorted pack on treats.
I'm sure I'm forgetting something but I've still got about a month or so till I see myself being ready to put it back together. Shipping delays are slowing me down so I'm focusing on cleaning everything up and getting it ready for paint. Thankfully all the internals look good. Going to replace bearings and seals as customary with all my purchases. Best to know what state everything is in and to ensure you can ride happy and mostly carefree! Can't understand people that run janky peds/motorcycles/etc.
Here's a few pics of how she currently stands. As a side note, I'm glad I took the plunge and tore it apart. Swingarm is missing 1 of the tabs that mount to the frame / motor!! Looks like it cracked right off. Unbelievable. Have to add that to the shopping cart....
Might start another thread titled "Things you wish you could tell the previous owner(s)". Id like to tell them that mopeds don't belong underwater (RUST!!) and that they shouldn't buy something they can't take care of!!
Anyway. Rant over. Back to tinkering. Thanks again everyone!