Iron Worker,
Try 52grns of H4350 powder and then work up to 53.5grns. I think with this powder and your 26" barrel, I am thinking you should be able to get to 3400fps without any problems.
I have owned two 6x284. My last 6x284 had a Krieger 30" 1-12 twist barrel. I was pushing the 95grn Berger at 3600fps with no problems. I was using 53grns of H4350, and I did not have any major presure problems. I was also using a custom action, so I was able to handle more presure. I was also pushing the 87grn V-Max at 3730fps. I ended up using the 87grn V-Max in that rifle because it was so accurate, and that barrel loved that bullet. Just watch your presures and work up to the higher loads.
If your not pushing the 6x284 a little bit, what is the point to having one. It is an awesome cartridge and it loves to be pushed. Have fun and let us know how it works.
One more thing, you should try VV-N550 powder. I never got to try it out of my 6x284, but I bet it would bump your velocities up without the extra presure. Read about this powder. It's more expensive, however, it's worth the extra money.
W.
W.