Both rifles, if unmodified from their original configuration, will have the older recessed bolt heads. They can be rebarreled with your standard Savage pre-fit barrel only if you replace the entire bolt. You cannot just change the bolt head because the bolt retainer pin is 90° off on your factory bolt bodies. Your only other option is to have a gunsmith fit new barrels to both rifles if you choose to stick with the factory bolts. If you were to upgrade the 300 to a magnum or heavy magnum barrel contour, you could then open up the barrel channel to get rid of that ugly bulge in the Bishop stock and have a very nice Sendero style rifle that should be capable of some very accurate long range shooting.