Having re-read your thread from top to bottom, I'll offer you some advice.
Get a different motor. The motor before you is trashed and requires a complete, top to bottom rebuild. That will cost you many thousands of dollars and probably 6 months of time. You need at a minimum: 4 new pistons and rings for an overbore, valve guides (probably), probably several valves if not all 8, seats re-cut, and you'll need numerous crank bearings, seals, gaskets, decking of the jugs, milling of the head, and THEN you'll need to diagnose why the motor blew up originally. And this is an important point, because until you discover that, you will only repeat the failure.
What you have is a motor that suffered a catastrophic failure. You posted that you ran the motor 5-10km without oil. That alone will burn up the crank bearings and possible the rod bearings. The heat distortion of at least cylinder 2 (from the detonating piston) is sufficient to require an overbore, which requires the other three to be done. At a minimum, that's about $500 before gaskets and decking.
Your head is glued to the jugs because the heat fused the gasket surfaces. You could have used a different approach to remove it before pulling the assembly loose from the bottom end.
I also have to ask because it's unclear: when releasing the head nuts, did you follow the manual and reverse the torque sequence, and equally untorque them individually? Or did you run around and loosen them up moving across the head in a visual sequence? Why I ask:
This technique of doing things that seem obvious is a trap many "inexperienced" people fall into. It's why we told you early on to buy the book. If you don't release the torque in reverse sequence, you run a very high risk of warping the head. That is why you now need to have it milled flat again. Not doing so, you will never get the head to seal and compress properly. Ever.
You may think us old farts are curmudgeons and would deprive of you of the enthusiasm and excitement of a hobby. That is completely untrue. We would rather help you, mentor you, and see you avoid the mistakes made by too many others. Isn't that why you came here in the first place? To learn? To get help?
So ditch you childish attitude and wannabe hipster lingo, and pay attention. Ask before you do, read and understand section by section the assemblies. Take things apart carefully, bag them up, document the parts, and you can get through this. Lots have already and you can be no different. But stick your foot in your mouth again, and you'll find your thread abandoned by those who would try the most to help you.
In summary; you have 3 options as I see it: 1 - replace the motor with a running motor, 2 - do a half-assed job of putting this together and end up broken down shortly after and ditching the bike, or 3 - prepare to strap in and spend thousand of dollars and many months doing it properly to result in a great running bike, that you will enjoy owning for many years to come.
Choose your path. There's no shortcuts in engine building.
