Well, looks like it was a simple fix. Pulled out the entire RAM expansion module as a unit, pulled the board for a quick visual (no leaking caps), and put it together just leaving the onboard memory and both drives unplugged... it bonged and booted to a flashing floppy icon as normal. Going to now try booting with the card installed and SIMMs removed to isolate the bad RAM.

So, that brings me to the point of, does the Classic require SIMMs to be installed as a pair or may they be installed singularly?