I don't know which kit you refer to but I personally would buy one of the rcbs kits preferably with a rockchucker press.This is a press that will provide a lifetime of good service.Some of the cheaper presses(especially the cheaper lee presses) are quite flimsy and will give you problems down the road.As far as reloading the 270 and 300 with one powder it is possible but there is no way to predict which powder will work best in each gun without trying them.A few powders that may work well in one or both guns are imr4350,imr4831 and h4831.