From my personal observations, any Lionel clockworks are hard to find, and running Lionel clockworks are even more scarce. I can't imagine you would find a Lionel windup that would bolt in place that could be considered "common". Hopefully, some of our members with a better working knowledge of Lionel clockworks will be able to chime in with some advice on compatible motors.
I don't know how much room there is, but it might be possible to find a Marx windup motor that could be retrofitted into the Lionel. The important thing would be to not make any modifications to the Lionel body; make all modifications to the motor, perhaps using custom made motor mounts. Marx windup motors are (mostly) cheap and plentiful. I have a prewar clockwork Lionel Torpedo that I have repowered with a Marx prewar ratchet motor, and it runs very well.