I scan all of them and post them here either as negatives or inverted as positives, or both as I did in the earlier posts. I suspect that some of these very excellent paper negatives were shot on the shoulder (slower) portion of the curve and then underdeveloped to lower contrast to get good contrast from high contrast papers. The alternative would be to shoot on the toe and overdevelop to get good negatives.
I have done both. In the case in point, I have avoided either, but I could shoot on the toe and probably force things to an ISO 50 or maybe even 100. IDK. I was not trying to do that.
You can push and pull papers the same way as film and without knowing the ISO, you can do this just to get the picture you want.
BTW, I "know" that the ISO speed of the Endura Yellow layer emulsion is nearly 100 and that the Cyan layer is about 25. When you add in the filter pack and orange mask, the overall speed to a neutral reduces speed to about ISO 25. I did that experiment at EK as well. You might want to see Bujor B's work on Photo Net where he exposed CA and Endura papers in camera with a Tungsten filter pack and got some good positive color prints by cross processing.