T$he best source of information on who you can find who is competent to fit stocks would be shotgun shooters, as they rely on a properly fitted stock to substitute for a rear sight, which are found on rifles, but not most shotguns.
The length of your neck can be as important to stock fitting, as your height. Of concern are 5 different dimensions:
1. Length of pull- measured from the center of the forward-most trigger, to the middle of the butt;
2. Drop at comb- measured from a line draw along the top of the barrel down to the forward edge of the comb of the stock, just behind the wrist;
3. Drop at heel- measured from that same line to the top rear, or "heel" of the butt;
4. Pitch- measured by standing the gun with the butt on a flat surface, and the rear of the barrel being against a vertical wall. A door jam works fine for this purpose;
and 5. Cast-on or Cast off. Cast is measured from a line drawn down the middle of your barrel and the top of the stock, and represents a deviation from that centerline at the Butt of the stock of some stated distance. "Cast Off" refers to the bend of the buttstock away from a right hand shooter' s face, usually of some fraction of an inch. "Cast-On" refers to Cast put on a stock for Left handed shooters. The amount of cast is chosen as that which will better align the shooter's eye with the centerline of the stock and barrel.
Because of rear open sights, most of us can adapt to shooting a lot of variations of dimensions on rifles. Scope sights on rifles require a better fit, but I know of few riflemen who are not serious competition shooters where scope sights are used that worry about "Cast". Cast can make a huge difference when you are shooting heavy calibers with heavy loads, as it tends to move Recoil force away from your face.
Talk to other shooters, to gun builders, and to gunsmiths to find someone who knows what he is doing. Its worth the extra cost to have someone do it right.
Once you know your measurements, you can modify other rifles and shotguns to serve you better.
I shot with a good friend who was a champion Trap Shooter, who was born, lived, and died in Urbana, IL., but had his stocks on his shotguns changed to his dimensions by a gunsmith near Peoria, almost 100 miles West Northwest of Urbana.
I was with him when he picked up a brand-new shotgun he had never fired, that he left with the smith to change the pitch and LOP. We drove immediately to the local gun club where he broke 24 of 25 targets on his first field, then shot a couple of 25s straight on his next fields, this time shooting from the 27 yd. handicap line. He loved the new gun and how it fit him.
My gunmaker fit the stock on my fowling piece to me, with several visits to him as the stock took shape, to make adjustments and confirm them. Because its a smooth bore, he put cast-on to the stock. But, at my request he also put a rear sight on the gun for shooting RBs.