I have built several rifles most using a tapered barrel. I like the tapered barrel becuase it reduces some wieght and allows the wrist area to be easier to profile and shape. I have one swamped barrel that I am hoping to build a rifle from.
As far as wieght is concerned, I am going to presume that you are looking to build a rifle designed to hunt, am I correct? I have found that using a short barrel (in the 30-33 inch range) greatly reduces wieght, is easier to carry, points very well,is easy to manuver through thick brush/trees/saplings and is very accurate between 50 to 70 yards. Those fabled 100 + yard shots are more difficult to make with a short barreled gun. Those small barreled jobs I make for a great hunting gun.