Let me first start off by congratulating you on reaching retirement and doing so with the resources available to tackle those great projects you have on the drawing board.

I'm 6'4" and weigh 200lbs....about 25lbs less than my football weight and some swapping of muscle to fat weight....but that's another story. I have a swimmers build and here's what my dimensions are as determined by Griffin & Howe and reconfirmed on 2 other occassions:

DAC = 1 1/4"
DAH = 2 1/4"
LoP = 15 3/4" for shotguns, 15" for rifles
Cast off = 1/4"
Pitch = 0

These dimensions are almost exactly what I had built into my Merkel and a rifle so stocked, comes up just as easy and natural as an upland game gun.

The type of iron sights will play a big role in your DAC and DOH measurements