ken ca
LOL, after I acquired maybe 20 infills, I collected all the stuff, steel plate, large chunks of aluminum for a form, a huge chunk of Lignum Vitae with the idea of making a dovetailed infill plane with adjuster. As it turned out my poor focus got directed to another project shortly after and that never happened - although it still could I doubt it will. My latest developing interest is metal casting and I can see a new rabbit hole developing.........

You're right as to the best way to make a user blade (I don't like the term "iron" I must admit, it's a damn blade), but I typically use my Keen Kutter "bedrocks" as users, the Norris planes are generally just for decoration although I do occasionally use an A2 or A6 just for fun. Their original full length blades may not be up to today's standard but they are good enough.
Cheers!