How to Hire for Code Refactoring

Our team is responsible for shipping code on a waterfall like schedule that integrates with tons of other libraries and is very perf, cpu and memory critical. There have been many folks that have worked on this for the last decade or so. What types of engineers would be interested in working in such an area? How would one motivate them? How would you go about hiring high quality talent? What level of experience should one look for? How to avoid fatal career limiting pitfalls?