This theater was across from Riverside Park on Jefferson according to the article below. There is a Riverside Park but it is off of Fort, not Jefferson. There was also a Riverview Park (now Gabriel Richard Park). Mike Rivest has an address of 7327 E Jefferson for this theater which is indeed near what is now Gabriel Richard Park.
The classified ad below indicates the address of this place was 1467 E. Jefferson. It is also very similar to the Dutchess if you look at the article below, which was supposedly near the Belle Isle Bridge, and again, near Gabriel Richard Park which was also Riverview Park (not Riverside Park). So it's all very confusing. To add to the confusion, the classified ad said go to 1415 Jefferson which is across the street from RIVERWALK PARK. UGGHHHHH!!!!!
Bottom line, I don't know where these joints were and I am a little suspicious about the "Dutchess" ever being completed.