Are you okay with the sight bulge on the factory barrels? If so, carry on. What twist were you going with?
I personally would keep the barrel at 22" and would possibly have some recontouring done if I wanted to drop a bit of weight or adjust balance of the rifle. (something like a douglas contour with some weight taken off the breech end of the barrel). One thing you don't mention is the weight of the rifle.
If you are okay with the shape/look of it I'd also consider a stock from Mark Bansner, if you are willing to do some of the finishing yourself to keep costs down. From personal experience they handle recoil very nicely. I would also consider a stock from Brown Precision. If you email Mcmillan they will tell you which of their stocks they inlet for the pre 64 action (more than you probably realize), likely they have something you would like.
I like your project, it will certainly be a handy rifle to have for your intended purpose.
