If you've created reports in 8.5 you can back save them to v7. I think from memory, you could open a report written in 8.5 with the CR8 designer (the only versions you could do this with) - however, bear in mind that if the report uses any of the features that were new to 8.5 it will fall over and die - in addition, Crystal would not support you/the client in this situation.
cheers...J