Nope not a special version, you just need the correct system enabler installed, which for a 520 is System Enabler 403. You need to make a boot floppy with a blessed system folder containing 403 so that it is bootable on your specific machine, then when it is booted, copy 403 over to the hard drive's 7.1 System Folder. After that it will boot right up. 
I made myself an almost universal 7.1 boot floppy for such situations which is actually a copy of the Disk Tools floppy from my set of genuine LCIII diskettes, but has all of the enablers that I am likely to use dropped into the folder such that if I switch hard drives (which I semi-regularly do due to failures or for testing etc), I can just floppy-boot it, drop the required enabler in and be on my way.
I made myself an almost universal 7.1 boot floppy for such situations which is actually a copy of the Disk Tools floppy from my set of genuine LCIII diskettes, but has all of the enablers that I am likely to use dropped into the folder such that if I switch hard drives (which I semi-regularly do due to failures or for testing etc), I can just floppy-boot it, drop the required enabler in and be on my way.