I found your question after your update was added, so I see what you found.
I'm sorry that you had problems, but based on how you describe everything, I think that you are trying to do things that are way beyond your knowledge and capability.
Removing the engine (yes, OUT of the vehicle) and TOTALLY disassembling it is the next step. Not trying to stick a replacement piston and rod back in and keep going.
You must first determine of the engine block is usable. It may be damaged beyond repair.
Next, you need that crankshaft out of the engine and inspected.
Then you'll have an idea if it's salvageable.
Sounds like you ran it with oil starvation. Did your startup of the newly reassembled engine involve a new (empty) oil filter?
How long did it run before the damage happened?
Was there loud knocking?
Or maybe you had open exhaust??
Take the bare block with main caps and crankshaft to a competent automotive machine shop for an initial inspection.
-Engine overhaul mechanic and general automotive mechanic since 1972