the norm for something like this would be to make a bunch of coupons and finish grind them after heat treatment. I have no way to do that. It's my expectation that I don't do much to cause decarb issues with steel, but I'm using CRA 26c3 and non-decarb ground O1 from starrett. It's still ground, though, and I've not noticed issues in use.
But too with that, I can hand lap the coupons to relative flatness, but I couldn't make the case for spending more or less a day to hand lap them and post-HT grind any possible decarb off.
Since I don't push the limits with temps, I don't think I"ll have decarb issues, but time will tell if only the toughness readings are usable. Decarb obviously spoils C-scale testing with a versitron if it's present.