There is also EPGY, which (like Singapore) has the advantage of having been around and working well for large numbers of people homeschooling HG/+ kiddos for decades.
I might try running through a beginning-of-course pre-algebra assessment for 'readiness' and see what needs work.
Most major textbook publishers have those included in the first few chapters of the book. Our public library and university library both have math textbooks in the reference section, so you could photocopy from one if that is an option locally.
Pearson might even have a sort of abbreviated version on-line-- PHSchool.com somewhere in the textbook companion sites, by the way.
