Coal to lands with a 250 Berger is 2.970". You will of course need a magnum bolt face. Rem 700 with an alpha or accurate mag dbm would work; or even a wyatts. A Savage model 116; or equivalent[, would be another good choice. The Tikka works well with the 3.4 ish mag box. Just about any custom action with a mag bolt face and 3" minimum magazine would be good. Barrel length should not be too critical to reach good velocity (24" should give you 2800). I would expect no more than 15' per inch, at most, velocity change. I would get a 10 twist barrel in 3b from Bartlein or #5 Krieger or equivalent.If you are going to shoot something in 200 to 220 grain bullets, most will have a coal nearer 2.400. I would expect powders in the Rl17 range to work the best with charge weight around 60 to 64 grains.
Hope this helps.......rich