This is where I got my decals for my Super A. Good quality. Best approach for the "H" decal is to cut it with an exact-o/box cutter knife in a circle (basically, cut the corners). Doesn't have to be perfect, but the decal is square and it won't fit on the hood under the curved part of the trim where the decal goes.
Also make sure you get the correct set. There are two, one for 1939-1944 and one for 1945-1952.