I would like to know how I can migrate a Persistence Disk (Google Compute Engine) from one project to another? If it's posible.
There is no easy way to do this on GCE, the only way is to go through the process of creating a custom image, exporting it to a cloud storage bucket (that both projects have permissions on), and then creating a new instance using the new custom image in the new project.
Follow these instructions: https://developers.google.com/compute/docs/images#installinganimage