Either shaped rod will be fine. Pick one that's rated for your intended use (which comes down to cross section), and don't worry so much about the shape. I wouldn't be worried to use the Scat I-beams at all on your build.
H is obviously stronger, which is why almost no OEM use them.
Actually it's not strength related at all... it's the manufacturing cost/ease that pushes us (FCA) towards powder metal I-beams more then anything.
Since the big/small ends are in the same direction as the I-shape, they can be easily formed, and VERY close to final shape which minimizes the machining costs. Even the hellcat rods are formed this way.
https://www.youtube.com/watch?v=azGg68B-Glk
