You bet it is Dave. But before you do anything to the parts, make a drawing of the rifle on a stiff piece of white paper. Start by drawing the barrel to exact scale, then add the lock so that the hammer aligns with the nipple. Watch how the lock screw is going to come through the stock behind the hook breech. Draw in the underrib and the ramrod. This will tell you where the bottom of the stock will end up. now draw in the triggers just as they are. Make the triggers cross in an "X" and place the sear bar on the "X". This positions the triggers fore and aft so that both engage the sear. After these critical things are drawn, then the rest of the butt stock and the rest of the forend fall into place.
Ron Long's triggers are also "short" vertically if I remember correctly. The other thing you can do is file out a new front and rear trigger. But adding to their upper dimensions is what I'd do if I was pressed.
