The post by Wobert, provides the link to obtain the Installer for the final release of Lightroom 6 which is 6.14. It is a complete installer, not an update.
With respect to this quote "Can I update LR6 to regain my old camera profiles or have Adobe locked them away?"
The installer will install all the profiles created by Adobe for LR 6.14, if you had created user profiles or purchased from other parties you will have to recover them from your old PC. So you will need to recover them along with your Catalog file if restore where you were previously. You will need to login into your Adobe ID and have the serial number ready to enter to activate the application.