I think your engine is seizing up. I'd refrain from starting that thing until you check the rods. It does sound like typical knock. You have good access to like 4 rods from dropping the pan alone it looks like. To access all rods looks like you need to remove the complete bottom assembly.
Crap temporary advice to say try thicker oil. If it's knocking, then it's knocking, what can you do? If it is knocking the crank journals will get scored eventually and you will be looking at even a higher cost of repair. It's not screatching metal to metal yet. I'm sure you can save the engine. Wish I wouldve told you don't start it. It's all my fault bro I feel responsible by saying shit like doesnt sound like knock, but it didn't, now it really sounds like knock.