If you are using the MegaRAID controller to manager the 7xWD drives then the order you connect that back to the MegaRAID controller does not matter. When the drives are initialized the MegaRAID it writes RAID data to each drives so they can be easily identified regardless of which port they are connected. I had a the same question for my LSI controller so I switch the drives around in the existing case to test the theory. It worked as expected so I migrated to a new case without issue.
Excellent, thanks for the info.
Though I have another question, is this the same case if I add a new SAS expander and connect the 7 HDDs to the SAS expander ports instead? (of course the sas expander will be connected to the RAID card)