Well I can help you with this! The short answer is yes, all your game save data will remain intact. (Because it saves the data on the Wii) What you should do is use WBFS Manager to get all the games off because sadly there is no other way to backup the games. Format it to FAT32 and put the games back on. Your done. If for some very odd reason the data doesn't work with the drive, then repeat the steps except format it back to NTFS. Hope this helps!
Don't forget to thank if this works!
And there is pretty much no difference between a WBFS drive that is FAT32 or NTFS.