You can find everything one needs to build your own heavyduty hoist at an ace or truevalue hardware store.
Maddog johnney has that exact hoist ,and while it's held the weight ,it sure shows the strain. First he had it under the seat as shown in there add. You can guess how that went. Then went to the rack ,didnt hang right , and in the end had to mod to frame .
Cost him a seat and the new hooks but did work in the end.
If it ever stops raining in chicago ,get with spring already, I'll ride over there and get a pic of his mod for you.