I bought a Stanley #7c off ebay a while back. It was pretty crusty, a borderline rat plane: rust, hang hole, pliers used on depth adjuster, sole worn from use, etc. The mouth was actually rounded over (a lot!) from shavings acting like sandpaper. In the process of rehab, I decided to make a new blade. I got some 1/8″ O1 and milled it to match the profile of the original iron. You can see how much thicker it is compared to a Keen Kutter iron (from a K7, which is a Stanley Bedrock). I had to open up the mouth a bit to fit the iron, but I had to do some filing anyway to get rid of that round over.
The cap iron screw is too short so I cut a step in the iron, which made the lateral adjuster unusably loose. So I made a little washer and just pressed it over the existing one. Heating treating an iron this big with a torch is a pain; it is really hard to keep it evenly hot, a little brick oven would be a good idea. As it was, I just kept the business end hot and quenched. As a result, I got some pretty serious warpage (if I remember correctly, I actually annealed it, flattened and re-tempered). Warpage isn’t a problem as long as the lever cap can press the iron flat against the frog (at the mouth), which isn’t that hard with a thin iron.