[2BadZ]

I recently pulled out my 79 TA that has been parked since 1996 and not touched since then.
I intended to change the oil before I tried to get it going. The oil filter was getting pretty rusty and I couldn't get my wrench on it, so I drove a screwdriver through it and took it off. Some sludge but some clear oil as well.
My surprise came when I pulled the drain plug on the oil pan. Nothing came out except a small amount of brown dust. Drain plug had been in tight, no signs of rust on the oil pan, don't recall any oil where I had it parked. Moved it once into my garage several years ago, and into a car hauler a couple of years ago.

Some questions.

Any ideas on where the oil went? I poured a little fresh oil through and it came out with some debris in it.
Anything I could do to clean the engine without taking the oil pan out?
Anyone have any idea on what to expect if I do partially tear it down, after what was likely many years without any oil in the engine?
Any other ideas or thoughts will be appreciated.