K.D.
You might find this helpful.
http://www.babycenter.com/0_chart-how-much-sleep-does-you...
I think it seems like a pretty good schedule. It's just a matter of you deciding do you want him in bed earlier and to wake up for one last meal at 10 or just stay up later?
You could try pushing back his morning nap about 30 minutes and that would push back his afternoon nap and then maybe he'd be ready for bed by 9 pm and he'd just sleep through the night. Just a suggestion.