Further update;

My son and I shot our new stocks yesterday. Going to take a little while to get used to the new feel but his Arthur Brown thumbhole shot very well, and it was a simple drop in and shoot it fit, right out of the box. We're going to bed it anyway, but very impressed with the machine work. Pillars were positioned very precisely and magazine box relief was absolutely spot on.

I had him photograph me shooting my Richards Micro Fit to see where my cheek placed on the cheekpiece. Looks like I can sand off the top for bolt clearance and still be fine.