There are lots of different perspectives on "Fit" ....on this forum...
But "Fit", in my mind, is best characterized - as the gun hits where you look. You put a full choke in it / shoot at a 3" spot - at 21 yards ( is the Point of Impact - POI ) right on the spot, or left or low, or high ....etc...
To correct the gun, so it hits where you look - is to adjust the "Fit". Maybe you need a little higher comb, maybe lower, etc ...or maybe a parallel adjustable comb. Some of the guns may have shims / you insert between the receiver and the stock - to raise or lower / or to move left or right .... some guns don't have the shims. Some guns have adjustable combs / you can raise or lower - or move left or right ....but they aren't common on synthetic stocks. Some you can add in after-market / some you're just stuck with what you have - because it isn't economically adviseable to do much to a relatively inexpensive gun.
To me - picking another gun - is about the adjustability. That's part of why, in my "target guns" - I shoot parallel, adjustable comb guns - like the Browning Citori XS Skeet models / or the Benelli super sport - because it has shims and drop in inserts in comb and in recoil pad. The Benelli system is incremental ...but its not bad. Some of my older guns are fixed - like my older Browning BPS pump gun Hunter models. On those I have to use a
"stick on comb pad" and/or alter the LOP with a different recoil pad....
"Fit" - so the gun hits where you look / is almost impossible to tell in a shop unless you have many thousands of shells under your belt ...and really know how the gun is supposed to feel / and what you see down the rib when you open your eyes. You can come close .....but you really need to shoot a gun at a pattern board / to get your Point of Impact ...and then dial in the "Fit".
When I was a kid / we didn't know anything about "Fit" ....we shot guns in the family, guns were passed down, etc ..... At some point, we figured out what made the gun fit / so it hit where we looked ( a vest, sweater, or coat combination ) or whatever ..... so when we put our face on the comb / it was hitting where we looked. On any "angled" comb gun ....like the Super Nova or the Browning BPS .... if you move up or back on the comb as little as 1/2" the muzzle moves up or down accordingly ... so your point of impact really changes. Its just the way it is / with angled comb guns ...
I know you started by asking about LOP ....but its all rolled up in this issue of "Fit" like OneOunce and Zippy advised as well .../ just be patient ...and shoot as many guns as you can before you decide.
As an example, Browning Citori 625 with adj comb / does not have a parallel comb. Its a beautiful gun .....but it has too much drop at the comb for me / so that gun, with that stock configuration, is a very poor gun for me... Most all of the Beretta O/U's have too much drop at the comb / and I don't like the slimmer area around the grip of their guns ...so most all of the Beretta's will not fit me either ...( all of which I've learned over many years .... )...
So you kind of have to develop your learning curve ...