I'm always ready to offer an opinion, for what it's worth.
If you have the means to do whatever you want, I think that the best configuration would be narrow lands, wide grooves, fairly shallow rifling. About 6 or 8 lands/grooves. Grooves would be cut so that there were rounded corners, and I would use Pope style rifling where just the corners of the grooves would be cut, and the middle of the groove would be at bore diameter. Lap the reamed bore absolutely smooth before starting to cut, and lap in a slight taper towards the muzzle, so that the bore tightens as the bullet works its way down the barrel. Lightly lap the completed barrel, just enough to get out any surface rougness caused by the rifling cutting, but not enough to round over the top of the lands.
The rationale behind all this is that the less you deform a bullet, the more likely it is to fly straight. Narrow lands will deform the bullet less, and cutting the grooves so that the center is at bore height seals the bullet tighter without having to deform it into the groove.The choke bore continuously tightens up the fit, so that the bullet seats tight all the way to the muzzle, so that gas blowby doesn't cut and start leading. The rounded corners leave less place for fouling or leading to accumulate, and clean easier.
Hope this helps!