I'd been kind of wondering about converting the larger DirecTV Ku/Ka dishes for FTA.
The Dish Network SuperDish is technically a bit too small, at 36" x 20" , but already has an FSS LNB mounted at the sweet spot. Some users are putting them up for the less challenging signals. I've said before I wouldn't spend money on one, but for the fellow who already has one for free, it's worth a try.
At an advertized 22.5 in. x 32.5 in., I wonder how the DirecTV Slimline would work out.? I haven't seen anyone come up with a clever way to mount a proper LNB, but it shouldn't be too difficult.
Just remember when you have trouble, "we told ya so"...