Ah, The Nice, a band for whom the term 'progressive' might have been invented - especially if you listen to their treatment of Dylan's 'My Back Pages' on the supreme 'Elergy' album.
Jackson Heights released another four albums between 1970 and 1973, the first 'King Progress' was on the Charisma label here, on pink vinyl no less, followed by '5th Avenue Bus' in 1972, and two in 1973, the 'Jackson Heights' album was their last for Verve Records in the States, followed by a return to Vertigo, their original home, Charisma's parent company. They released an album called, believe it or not, 'Bump And Grind' which given the band's style, and Jackson's vocals, has to ironic in the extreme!
All the albums were re-released on CD, but are probably deleted by now.
As we always say on the Answerbank Music Section - check your local dealer, then hit the second-hand market, and the Net, you should be lucky.