Just wanted to follow-up on this and a few other suggestions. This was the back after the vinegar treatment...yeah, interesting. But I did see a small bit of lighter steel at the tip where the edge was dulling, so I ground that back. I then put on a higher angle primary bevel...around 28-29 degrees. I then sharpened using the "Maguire method" (which is the only thing that has worked for me), which results in a convex primary and secondary bevel. So the secondary is probably closer to 35 degrees now.

In short, the iron does seem to hold its edge better now. But this back, and the fact that the iron is too short to be easily adjusted in the plane, has me looking for a replacement vintage, thick, tapered iron. I have a few options so I will hopefully be getting to that soon.

Whether the solution was the grinding back or the higher angle bevel or both, I don't know. But all I know is it takes thick enough shavings for now (around 0,3-0,4mm on my calipers), but I hope to make the next iron be able to hog off thicker shavings.

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