Unfortunately, Mac OS 8.5 and 8.6 are still considered as commercial software, given that they were never released for free by Apple. As such, even though its 14 year old software, any unauthorised copying of it is still considered to be piracy, which we don't do here. If you just want to get your 5300 running again however, System 7.5.3 is available for free from Apple, and can be updated to 7.5.5.