You will need to migrate to a new version of Find compatible with CMS 8.
Changes should be minor. If something is called Page/Pages rename to Content/Contents and along those lines.
Also if you have conventions and customizations for UnifiedFile these will need analysis.
I'm in the middle of migrating and Episerver CMS 6R2 webforms with Epifind 6 site to Episerver CMS 8 based on MVC. Is it possible to reuse the EpiFind 6 implementation on the new Episerver version or do I have to migrate to a new implementation of Epifind (version 8 or even 9)
Thanks in advance.