Do any of you homeschool your children for high school level subjects? If so, can you recommend a resource for putting together a college-ready transcript?

Our 8yo is doing high school level work in many areas, and I need to learn more about the best ways to document his progress in terms of preparation for the college admissions process.

I've looked at a lot of books on Amazon, but it's difficult to tell what would be the best resource, so I thought I'd ask for advice.

Thanks in advance!
Tara