Kobe makes one that supports 7-8.5' ceilings. See link below.

KOBE RAX2130SQB-WM-1 Brillia 30-inch Wall Mount Range Hood, 3-Speed, 750 CFM, Fits Ceiling Height 7'-8.5'

(A wall mount range hood is probably not what the OP asked for.)

Mating to a 7.5 foot ceiling should not be difficult; even Wolf's large Pro Island hoods are only 18 inches high, leaving the base at 3 ft over the counter with a 7.5-foot ceiling. And higher helps the view across an island. However, unless the cooktop is only 24 inches, a 30-inch hood is too small for an island application. One needs to overlap the cooking zone on all four sides to account for rising plume expansion, and throw in a bit more size to account for cross drafts, depending on location.

In any case, to say that the kitchen has a duct is far too little information. Where is the duct relative to the cooking zone, what diameter is it? Is there a blower at the other end or do you need one in the hood, etc? Can the duct be replaced?