I used to run hotter without issue, but keep it to 1250°F at this point. Is this a current picture or when you were still assembling it? You need to install the anti-vibration clips on your metal lines or they will break from the vibration. You're missing the corner nut on the valve cover and the timing belt bolt/washer. Hopefully none of the hardware is waiting to fall into your timing belt. You're dipstick looks wonky. There's a fair amount of the pump sprocket showing and none of the belt. Is your timing belt is tracking correctly? Your alternator top bolt has backed out a bit. Is the fat red wire hanging down to the right of the oil filter live? The braided stainless oil supply line should get zip-tied at minimum. If it is allowed to vibrate long term it will act like a saw and cut through hoses, wires, etc. Your strut top bearing nut is about to fall off. What's with the wire grounded to the valve cover stud?
...BTW your Bieber avatar is awesome.-Malone
I'd say you got lucky. Once you remove the sprocket inspect the crank nose well, hopefully it's not damaged.
I'm really confused about that crank sprocket! You say the motor was just rebuilt - but the crank . . . wasn't removed? Did the motor just get some new gaskets or something? Also, I'm having trouble imagining what could cause that kind of damage!