While we don't yet have a dedicated case for the Boss GT-1000 Floor, one of the cases in our UNISON line may be a good fit!
The dimensions we have on hand for the Boss GT-1000 Floor are: (18.2 x 9.8 x 2.8). If that aligns with what you have, we would recommend looking at the UNISON CUSTOM EDITION: (15.1x 13.7 x 4.7) inches.