I'm running an un-hacked UBB.classic 6.7.1 with the following stats:

Total members: 9,116
Total forums: 57
Total topics: 69,119
Total posts: 609,023

Any guess on how long it will take to upgrade and import posts to the new product?

Besides the obvious (deleting posts and old member accounts) are there any things a person should do to his board now that might make upgrading/importing any easier?