My K100RS has what I would consider excessive dive when I brake.  I bought some Wurth fork springs, thinking that at 45 K miles, the OEM fork springs may be a little tired.  (BTW, the Wurth springs are not labeled for their weight, so I've no idea if they are a different spec. than the OEM springs.)  If I change the springs, I'll also change the fork oil.  My Haynes K100 manual seems to have vanished among the clutter of the garage; I looked at the riders manual for the bike, but wasn't able to find the mount of oil the forks should contain.  Can someone tell me how much oil the forks should hold?
In a related issue, my understanding is that a bit less oil would make the fork action more progressive and a bit softer; more oil should make them less progressive and a little firmer.  Correct?
Should I fill them with 10W oil?
TIA

http://www.motobrick.com/index.php/topic,666.0.html

A wealth of info available here...

Speaking with a mate who owns a bike shop and they put some car automatic transmission fluid in with the fork oil. Apparently it helps to keep the seals healthy.

I use synthetic Auto trans Fluid, it works well for me but I am a heavy person and for a lighter jockey it may be a bit heavy and stiffen the front too much.

Yes, more fork oil will make forks stiffer.

FYI: There are no standards for fork oil weights so 10W from one manufacturer does not necessarily have the same compressibility as 10W from other manufacturers.

I have always had good luck using Honda SS-8 10W fork oil in all of my Ks.

It's odd that there is no standard among manufacturers of fork oil.  I've no idea what is in my forks now.  According to records, it was replaced by a BMW dealer while the bike was with the previous owner.  
For my own work, I'm going to use some left over Bellray 7 weight mixed with some Bellray 10 weight, combined with the Wurth springs.  Fingers crossed, hoping this will be an improvement for the Marzo fork action.

With forks and oil it comes down very much to what suits you. What you are planning is a good starting point and would give good handling. With a bit of fiddling at the edges you will find the sweet spot and all your numbers will fall into place.