We consolidated a few dozen W2k3 servers and a Windows SAK-based NAS system into our EMC Celerra NS700G. While I don't have much to share on the task side, I have quite a few gotchas and pitfalls.
First - categorize your data to move! Sure, every SQL database is important, but you may have to get Finance's Excel spreadsheets up well before Engineering's AutoCAD drawings, so plan accordingly. As much as I wanted to bring up non-essential resources first, management wanted all of their tools and services up first. We had to plan to move our largest, busiest databases first, check consistency and get them up and running. We focused on mo
Second - plan your service dependencies well! In our case, we run anti-virus software on external W2k3 servers, on a private VLAN. We configured the NAS to stop serving files via CIFS, if A/V servers were not available. Our sizing estimates called for two A/V servers during peak load. It turns out that our Windows admins also run other applications on our A/V servers, which gave us sub-optimal A/V scan times. We ended up deploying another A/V server, since it was easier than getting them to stop running other applications on the existing A/V servers! Check and double-check anything that runs on an external box - backup software, A/V software, quota software, etc. Make sure you have enough CPU/network/disk in them.
Third - consider third-party migration tools and consultants, if your budget allows. Shareware and freeware tools can execute the copies and check permissions, but very few of them are able to deal with serious problem. Shareware will probably move 70TB of your data well - the last 10TB will take so much hand-holding, it might just be worth the cost to have a custom solution handle more of the problems. You'll find that moving data is easy - it's keeping the permissions and quotas intact that's hard.
Unfortunately, I can't recommend too much in the way of whitepapers or books, but I think the articles at SearchStorage cover quite a bit about NAS in general and server consolidation in particular. Quite a bit of it is directly applicable. Please message me directly, if I can be of further assistance.