Cleaning and restoring bronze

[BestMate]

I got this old porthole and need to know how to clean it up somewhat. It's not just tarnish but it has years and years of crude and bumpy type growth on it. What process can I do to get it back to at least some sort of decent condition so that I can install it in one of my interior doors?

Here are some photos of the over diameter, the glass opening diameter, and thickness.