Ronit Bird has several books and resources to use for students who have dyscalculia http://www.ronitbird.com/
Also, does your child have a rock solid understanding of placevalue? Does he thourally understand how to +,-,×, and ÷ fractions, decimals percents and whole numbers? Algebra can be the place that any prior holes really shows up. If you think there are holes, a solid, straightforward math series like Rod and Staff could help you fill it in. I know Kate Snow (from https://kateshomeschoolmath.com/ a math teacher and curriculum writer) recommended that series for students who struggled with math. It only goes through 8th grade as Mennonite schools often stop there, but it is slow, methodical and complete.
I would worry less about how high you get in math and make sure a solid foundation is there to build on or just use in life. It would be better to have a solid base and only get through Algebra 1 in highschool than shakely get through Algebra 2 and Geometry before graduation.