I dont see many similarities with my older instrument and I want to avoid speculation on this, I can however make a few comments now that I can see a lot more detail.
The metal valve guides are robust and suggest early manufacture and high quality.
Various hexagon shaped parts have been seen on artisan models and this also suggests higher quality.
The water keys are slung beneath the tubing in the manner of a trombone and this is fairly typical of a manufacturer that has a history of manufacturing trombones prior to manufacturing trumpets.
Olds for example manufactured trombones before trumpets and adopted the underslung trombone style water key on some of their trumpets, they also adopted brass valve guides very similar to yours, although we should not draw conclusions from these two facts.
Martin adopted trombone style side action water keys on their Committee horn and you cant get better than that.
As to the hexagon shaped parts Bach used hexagon receiver ends as did Olds and several others.
I also believe I see Nickel balusters on top of the brass valve casings, this suggests the valve casings were fabricated in two parts in the manner of Bach Strads, and the Bach strad is about as good as you can get.
Additionally all the ends of all the slides are rounded like a bead, I have seen a lot of beginner intermediate and pro horns and you tend to not see this on either beginner or intermediate horns but you do see this on some pro horns.
It looks like a great deal of money and care was lavished on this instrument during its manufacture.
There are so many elements that singly do not prove quality but when all are taken together they suggest quality.
Adding everything together I have reason to believe this horn could easily be an intermediate or better instrument.
But none of this really proves anything. An instrument can be made well but still play poorly.
There are many factors that could relegate this instrument to beginner or worse quality, the resistance, the intonation, possible valve wear, bent or ill fitting parts due to damage, we cannot yet know where the gremlins are.
The only opinion that will mean anything is that of a competent player following an extended play test.
Regarding the mouthpiece, I believe that the mouthpiece and instrument should be matched to each other so as to deliver the timbre and tone that the player aspires to.
My mouthpiece is unlikely to be of any value for you I have many and can swap them to discover a good match.
You may need to swap mouthpieces out to reach the tones you are looking for.