Yup, you need Halbach arrays; it about doubles the field, and the lift is proportional to the square of the field, so you get 3-4x more lift; and takeoff happens at much lower speeds.
The number of people that have been able to make a working inductrack design is very, very short. The biggest problem seems to be getting the system up to a speed where it actually lifts, ~24 mph is not that low really; although inductrack II is supposed to lift at about 5 mph.
FWIW I've made Halbach arrays. They're not too hard to make provided you have a flat fairly thick sheet of iron or steel to act as a flux shunt while you build it (needs to be about 1/4 the thickness of the magnets) and build them on that, with the flux side down, and then stick them to a backing plate and then slide them off when they set. Provided it's thick enough the iron/steel attracts the magnets very well, and friction holds them in place (more or less), although you'll have to clamp it when you glue it since the intermediate magnets popup.
If you don't do the flux shunt trick, the magnets will fight you oh-so-very-hard.