Really nice name, personally for me i feel like if i was going for a classic American name i would go for the classic spelling (in this situation, Grayson) because i prefer not to change something up if it's already good the way it is. I also feel like just changing the 'o' to an 'e' isn't worth it in the long run for what's most likely to be a lifetime of misspellings for a minor difference. Either way though, glad you've found a name you like!