My go-to would be All About Spelling. It is a scripted OG-based spelling program designed for home use. It does require direct instruction by someone (you or a handy young adult). At his age, he probably won't need to spend a lot of time at the lower levels (there are seven levels altogether), but I would highly recommend going through them anyway, just in an abbreviated form, as there are often odd gaps that dyslexics have, especially in phonemic awareness.

...pronounced like the long vowel and first letter of the alphabet...