I'm experienced developer with more then 15 years background. I use MEAN stack last 3 years in various projects (from small cms and custom sites to huge project for Deutsche Bank). So I have ann necessary skills to complete your tasks in time and money. Please, provide more details about your needs: what is current state of your project, is you need only modificate your existing code to work with different back-end, or you want to add new features, etc.
I have one additional query: why you choose this way to migration? Now you can deploy your own Parse server and switch your app to it. This way is easy and cheap.