If you want an inexpensive fix, go with stiffer fork springs. Try www.racetech.com to get a general idea of what spring rates would be good for you. Also, another thing to take into consideration is the condition your fork is in right now--how old is the oil, what weight oil are you using, are the internals in good shape, etc.
A decent mod for these, is the race tech "emulators". It actually makes them decent, and are easily installed and adjusted by the average person. No doubt the already soft spring are also "sacked", being that old. A set of straight rate springs will greatly help. I have never been to fond of the "progressive" springs you see advertised for this application. My .02
He will sell you the same spings for alot cheaper than race tech, and they are the same springs made in the same place! Race tech emmulators are just a quick fix. get a real revalve you will be much happier and have more money left overto go riding with. Adding nitrogen to your forks is the wrong way to go, up your oil level in 5mm increments
I'm not a fan of Progressive springs, either. I had them on my 600 for a while, and didn't like them. Why not? The initial spring rate was much softer than stock (.36 kg/mm vs. stock .41), so just sitting on the bike would compress the fork quite a bit. What this did was make the fork harsh because it was already a good part of the way through the travel, where the fork action becomes more stiff.
After I installed straight rate springs, I found that the bike handled much better everywhere, especially in roots and rocks.
ssuperbike, are you familiar with the fork on the 86 XR250? what do you consider a real revalve? do you mean a damper rod modification, as in welding and resizing the orfices? The product I'm talking about are "cartridge emulators", by Race Tech. I'm not a fan of much they do, but this product on this application, is a good mod. It actually gives you some "valving", although crude.