Very interesting challenge. You stated that this aircraft was built in the same era as the Alco Sport. Could not find much about the Alco sport plane on the web. I did find some information about an aircraft called the Arrow sport. It was stated that the early Arrow Sport, built in 1926, initially offered a 6-cylinder 60 hp Anzani engine as well as the Detroit Air Cat engine; however,
the 5-cylinder 60 hp Le Blond engine soon became the standard production engine.
The 6 Cylinder Anzani engine was a built in March 1910 by merging two 3-cylinder units together, one slightly behind the other and at an angle of 60° thus producing the first two-row radial. The aircraft listed in Wiki are biplanes. It is known that a number of Polish aircraft were fitted with the Anzani, the R.W.1 being one example. This was a high wing braced monoplane.
So was this aircraft 1920-30?