I would highly recommend changing your proposed route to take gates pass road (then onto Speedway) back over to I-10 rather than continue down to Ajo. It's a bit more fun, with several scenic views. Unless you're planning to hit the old tucson studios on the way past.
Personally, I'd probably also continue down 77 to take Tangerine over to I-10. The view of the catalinas as you come down past Oro Valley is a sight.
Personally, I'd probably also continue down 77 to take Tangerine over to I-10. The view of the catalinas as you come down past Oro Valley is a sight.