I can't imagine fitting anything resembling DL on a cassette. Not just because of the limitations of games on audio cassettes, but because that means it must have been a C64 at *best* and I have no interest in some POS C64 game just because it happens to legally say "Dragon's Lair" on it.
I played the Amiga one back in the day, I think it was 7 3.5" floppies. It was basically the entire game remade using huge rotoscoped sprites. Aside from constant disc swapping and many missing scenes, it was probably the best Dragon's Lair for home until the CD-ROM era. It think each floppy basically held a scene with the finale needing floppies 6 and 7. This was a long time ago, but I think I'm correct. It was the most floppies I had ever seen for something until Windows 98's mail-order-only floppy version which was...I want to say 13+ floppies.