That's an interesting thought, perhaps we could have nomintations for some of our favourite games to be vgaspec levels? I'm sure I'd jump at the chance to do Super Mario Bros Lemmings
I think you'll have a hard work doing that; I don't know Super Mario too much, but I remember it as a very colorful game. The limited number of colors might become a difficult problem there. However I'd be interested in the result.
For my next set I'm making a level with Supaplex graphic. The limited color palette gives me some problems: I can only use 4 or 5 of originally about 40 sprites. It uses glitches, but I could also make one level for the remake without.
(Obviously I like the idea of special graphics levels.)