Analog board checks out, so my repair there was a success. 
Unfortunately the logic board is toast... me and Wackymacs on IRC, with his copy of Larry Pina's book handy, were unable to determine the cause of the "Sad Mac" as it had no hex code listed below it... just garbage print. Unfortunately it's beginning to look like one of the IC's could be to blame, unless capacitors could also cause this issue (i've replaced 2 out of 3, ran out of the last one).
So... looks like i'll be in the market for a 512k logic board then! Doesn't need to be a 512Ke board or anything... I can provide the ROMs and the 800k drive for it, I just need the board itself. I'll see what I can come up with anyway.
Unfortunately the logic board is toast... me and Wackymacs on IRC, with his copy of Larry Pina's book handy, were unable to determine the cause of the "Sad Mac" as it had no hex code listed below it... just garbage print. Unfortunately it's beginning to look like one of the IC's could be to blame, unless capacitors could also cause this issue (i've replaced 2 out of 3, ran out of the last one).So... looks like i'll be in the market for a 512k logic board then! Doesn't need to be a 512Ke board or anything... I can provide the ROMs and the 800k drive for it, I just need the board itself. I'll see what I can come up with anyway.