This is why people have written coding standards (with defined naming conventions) and have code reviews!! Make sure you implement those procedures right now, to prevent his from getting any worse in the future.
Also for around $300, SQL Refactor™ is an excellent tool. If you were to use search and replace, you'd have countless errors and spend hours and hours editing code. I wouldn't even consider using anything other than SQL Refactor, and would never even try using a manual search and replace method on something as large as you describe.