Yeah, I was more asking whether Retro thought 4130, 6061 or other steel variant offered a more advantageous platform. It would be hard to make it from scratch and be "better" without lots of trial and error. Simply making a frame doesn't insure you've improved the original. Now, a modern tubing version of the original would be keen, but to what purpose? One can brace and alter the existing some without destroying its character or charm, and factory fitment.
I've toyed with this idea, I just haven't seen a great example of a new frame that screamed "I'm the one!" for a street bike.