Hello,
i released the version 7.5 of Scheme+ for Racket.
https://github.com/damien-mattei/Scheme-PLUS-for-Racket
it is also available has a Racket package here:
https://pkgd.racket-lang.org/pkgn/package/Scheme-PLUS-for-Racket
it contains a few examples in this directory:
https://github.com/damien-mattei/Scheme-PLUS-for-Racket/tree/main/examples
Also released is some versions for Kawa and Guile on my github.
Regards,
Damien