24" in about a #3 contour for "hang" and a smidgen of extra velocity--that's on the long end. Short end, I'd go no less than 22" unless you are building something for specialty use.
Why don't you have it installed at 24" and see how it feels all up? You can always have it cut later.
Barrel contour is often ignored in this process. I like a short chamber area, a fairly rapid reduction in diameter through the forend section and gentle taper to a bit thicker muzzle: Too many bolt action rifles are center-heavy. Ruger 77's are notable examples. When you lose "hang", you lose steadiness and a sense of where the muzzle (the aiming part)is.
The Winchester Featherweight contour can be modified to taper less and have a thicker muzzle area--giving more of this type of weight distribution.
