Found this old thread and your still around so I thought you might still be interested.
I reshape old or even new carbon steel tramotina blades. I have a few but only have 2 here at the house right now. Anyway here are the shapes I went with on these 2.
I use this one around camp a lot
This one I use for about anything....Just cleared about a mile of brush around the perimeter of a property with it a couple weeks ago.
Tramotina is hard to beat and you can buy them in bulk(6) for about $7 per. These are the blades a lot of people in countries where they make a living with a machete use.
You'll want them to be tip heavy(tip wider than the handle)