Ok ,I have no idea what the GVWR of our bike is (could you tell me?). Fork-15w or ATF , Rather than go to chain ,I'd go with a Kawasaki front pulley from DAVE and keep the belt drive.  60 mph=4008rpm stock , would be about 3688 with the pulley , peak torque occurs at about 3400 ,so would be ideal for moving you and your passenger at legal speeds .I 'd invest in a set of taller ,progressive sprung shocks verses chain drive . I ride with a combined weight of 345lbs (two up-90% of the time) with no problems ,and have for over 16000 miles.

so please explain what  taller shocks have to do with the final drive ratio on my bike?

Everybody Knows you get the rear end up
You're going downhill.
You get higher top end
And
Better mileage.

    I love that you ask about types of fork oil and chain lube ,I think you need to be reading Consumer Reports. the bike calls for 15w ,pick your poison ,this isn't a testing lab.
    I don't run a kawa pulley it's counter productive ,as will chain drive with a lower ratio, the motor turning slower produces less hP  while your asking it to move more weight at higher speeds . Acceleration rate will also decline making passing more difficult, as well as higher cruising speeds.
    Longer shocks would add passenger comfort ,more ground clearance (higher lean angle without scraping you foot pegs) and faster steering due to reduced fork angle.
     As for gvrw ,I 've never seen it in print ,never got a manual with the bike ,I guess after having several they figured I knew were the key went.
    But heck you seem to know so much I'm surprised you asked any questions at all.
                         good luck!
 

The members of this forum tend to avoid chains and lube on their motorcycles, as previous experience has left them with a disdain for the mess and required maintenance - and it is impossible to state that one lube is the "BEST" .  I have owned motorcycles with chains, and the new O-ring and X-ring chains are much easier to maintain than the old ones - but they still are labor intensive and messy.  I have tried the Chain Wax, Klotz, and am currently using Lucas......still haven't found one that is wonderful.

The forks on this bike are primitive, and don't really require anything special or expensive.  ATF works just fine in them....you can spend more money for dedicated fork oil - it won't make much difference in the fixed orifice.

MarcosS40, I have always had good results lubricating my 0-ring chains with a light oil.  I use LPS-2.  It dries to a light waxy finish and protects the chain from corrosion fairly well.  It's my understanding that 0-ring & x-ring chains capture the factory lube (hence the o-ring) and all that is required for maintenance is periodic cleaning and then a coat of light oil to protect the exposed plates and rollers from corrosion.  That process has worked very well for me over many years and chains, and keeps the mess to an absolute minimum.

Regarding your suspension, I suggest you PM member "Gary in NJ".  He seems to specialize in suspension systems and everything that I have seen from Gary looks to be spot on.

Good luck and try to keep that GVWR as low as reasonably possible.