I remember playing it at my father's work many years ago, and I'm pretty sure that computer had at least 7.1. I can't remember if there were any Help Balloons, but Taskmaker was on that computer.
On my PB 160 with 7.1, it loads to the startup screen, loads all of the windows, than shows a blank box and crashes. Deja Vu and Uninvited work fine on the same system.
Unfortunately, the standard version of Shadowgate is not System 7 compatible, but there was a hacked version floating around at some stage that supported some version of System 7.