After being healed by Dende, I have his normal power around 600-800k at the most. My guess is he wouldn't have been much different than he was on Namek. He asked Piccolo if he was still training every day, but I doubt Gohan actually was.
A pretty decent amount of time goes by between his last battle on Namek and the arrival of Mecha Freeza. I can see Gohan staying the same as you guys mentioned, but wasn't as sure about him making any huge gains. Or gains of any sort. I'd say he maybe snuck off to train once or twice during that time, if I am so inclined to create some sort of "side story" in my head. But that would probably be to get away from Chi-Chi and go play with Higher Dragon.