Try these settings. They work great on my '99 300 E/XC. Of course, every bike is different, and air density varies, so these are just starting points. But I ride at 0 to 3,000 feet in hot, humid Texas, and my 99 300 E/XC runs very crisp at these settings. It has a stock pipe and reeds.
pilot - 48 slide - 6.5 needle N85C-2 main - 172
You may find that on the 92 octane gas you have a little clatter under a load. I recommend Super Hunky's mix of one gallon race gas to four gallons pump gas. VR's gas is good, though it's a blend, and some purists don't like that. Phillips 66's Base 32 is comparable in price (about $5 a gallon) and is not a blend. Both are pretty readily available. I use the B32.
As far as oil, Ive tried a lot of them. Nothing smells better or protects better than Maxima's Castor 927, but it's dirty, dirty stuff. It will spooge your muffler, drip down the headpipe, and encrust your power valve. LCR racing here in Dallas recommends Motul 800 at 66:1. I am plannig to adopt their recommendation, and will report on results.
Good luck with your 300. I love mine. I had the four-stroke bug pretty bad recently, and rode every KTM thumper at the dealer. Honestly, that cured me. I wouldn't trade my 300 straight across for any one of them (let alone for an inferior brand). They're heavier and more sluggish. I like a nimble-feeling bike, and they seem to lumber. Might be great in more wide-open stuff, though. I ride mostly woods.