Working around an average standard is the best practice in most cases. There is only a small percentage of builders that really know anything about fit and an even smaller percentage of buyers.
And, unless some extreme is encountered, "fit" by modern standards, high end English shotgun for example, is practically irrelevant to the longrifle.
They are not intended to be pointed, they are aimed.
They are often shot off the arm not the shoulder.
They are often shot in a
stance that is FAR different than for a shotgun. So shotgun fit won't work anyway.
I would also point out that is difficult to build a kentucky of many schools that can be made to look right if made to some specific measurement of drop or pull. If we look at RCA and look at guns that don't quiet seem right somehow it will be found the LOP is over 14" in most cases, or under 12.5 perhaps.
I have read old accounts of the British mockingly describing the Swiss and German Schuetzen shooters stance and how they filled their chest to stiffen it and how they expelled it after the shot. But the people making fun of the shooting style probably could not finish in the top 90% if shooting against them. And no a Schuetzen rifle is not fit like a shotgun either.
When making a rifle for BPCR Sil. there are rules. So I used to build to just slightly more than the minimum drop at the heel and with zero pitch. 2 reasons, the rifle will jump less in the cross sticks, less felt recoil and it allows the face to contact the stock a little better when shooting rams.
I try to build longrifles so they look right and the pull is about 14" or maybe a little less. To long makes it hard to recreate the look of the orignal if it has a 13.25 or even less pull.
Some cast off, drop depends on the school but I don't agonize over it much but tray to keep them fairly straight. If done within reason the rifle will come up with the sights pretty well aligned.
Building fowlers? That's a shotgun. They need to fit like one since they are pointed.
Dan
