"STOGOS" was the trademark of the short-lived Stotz & Goessel, Erffastr.26, Suhl, company. They called themselves "gun factory,export, wholesale". Johann Stotz and Leopold Goessel founded the company in 1923. Partnership dissolved 1927, sole owner Stotz. Finallly failed in 1930, remaining stocks taken over by Wilhelm Knopf. So the rifle is not pre-WW1, but made between 1923 and 1927. It is made on a scrubbed WW1 Gewehr 98 action, as usual for the 1920s.
As to the chambering, only a chamber cast will tell what it really is. IMHO the most likely candidate is the 7.65 Mauser, originally adopted 1889 by Belgium and Turkey, but now known as 7.65x53 Argentine. The actual max case length of this number is 53.5mm, so it was often called x54 too. The rifle may well have been made for some Belgian bound for the Congo, intended to be used both against beast or man, using the standard issue rifle cartridge.