i got to this point after 8 hours.
marking and cleaning as i went.
that is the box the heater core actually sits inside.
had to buy some 1" weather stripping for it, as the oem one did.
be carefull on the copper pipes, they are soft. but can take a fair amount of tugging.
i bent the tips trying to get the engine bay hoses off.
ended up pulling the hoses w/the heater through the firewall, and removing them after it was completely out.
but, wow, when i turned the core upside down, the crud just bulged out.
and it could've been acid washed/cleaned, but after 20+ years, i figured a new one is much needed.
any ducting will work.
and i havent got the whole thing back together yet (blower stopped/ no power to the relay)