Hey beard, welcome back to NICO Club.
You can use the FSM in your inspections. We don't have the '93, but we do have '94, which should be close. Here's a link to that:
http://www.nicoclub.com/FSM/Hardbody/1994/
There is a lot of talk about KA24D lifter tick and that would go into some detail about where you're working. Here's one that is really good, but the dang pictures stopped working and were removed, so maybe just read it and pair it with other pictures:
http://www.nicoclub.com/archives/ka24e- ... epair.html
I think if your cam lobe is in the way, the lifter ain't gonna move and if it's out of the way it should be able to move. Look for the holes and oil path mentioned in the article above.
Did you ever figure out your heater core replacement options? I see that was never replied to, so I figure no one knew back then. Maybe you know now?