3/8" from top of plunge line to the spine at present. The plunge line will go higher, but not to the spine. My goal for this build will be 3/16". On the 4" hunter the distance is 3/32" with a subtle curve throughout and forward slant. It was a P.I.A. for me to do by hand, although no guts no glory. So I just did it.
Willi71 advised me about eliminating the 90 degree internal angle thereby greatly reducing stress in that area on the 4" knife and I did that. The tang on the 8" was wrong and I fixed that mistake. Your comments and advice, also those of other craftsmen are very much appreciated. The fresh pairs of eyes most often pick up mistakes or prevent major problems from occurring. Thank you.