Major update on the SCI1.0 template: it has been redone, using the Mixed-Up Fairy Tales demo as the base. That means the interpreter and system scripts are newer, and it has separate drivers for music and digital audio! With that, GMBLAST is not needed any longer. Ego is now played by the white boy from MUFT, and his head moves normally in real-time (as opposed to using cycle speed like in SQ1VGA and SQ4).
Now I see why those timer bugs were present in the CD-ROM version of SQ4, but not the floppy version - it all comes down to the Game class's doit:, which had things like a "gameTime" global added in around late 1991. Unfortunately, the game-specific scripts were not adapted for this upgrade, thus you get things like Roger's head moving super-fast, for example.
You know, I think the SCI16 series of game templates is ready for action.