I just finished my AV mod for the original HVC-001 Famicom, and was met with awesome stereo sound.
However, the composite video output was not so wonderful: In Final Fantasy II, the text which should be white is black, and there is a great deal of noise and "scrolling" screen trouble on the worldmap. It looks horrid.
I followed the instructions at Famicom World, but ran ALL of the cables which connect into the circuit board/output jacks out the back of the famicom and into an external project enclosure. This was to avoid drilling holes in the thing.
Any suggestions? I can provide any other information as necessary.