you can play even further generations back in time with the style converter disk!

it is a most odd assumption that your disks will not work given the evidence of the history of features of the keyboards.

by now all your disks should be on your sx6 hard disk. Make a techmanager backup, they will all be in 6500 format. That guarantees they will load in the 7000, probably sounding better than if you leave them in older formats on their original floppies.

Print out a directory structure from the techmanager, now you have a record of which files are where, you can copy selected files to fill whichever size of flash memory card you buy for the 7000, and update with new different files when needed. It will be very simple...