"Big end" is our term for the connecting rod, or piston rod, where it mounts to the crankshaft. That is its big end, the little end being at the piston.
My reply already shows the Head bolts tightening torque and sequence.
"Angle tighten to 90 degrees" has nothing to do with rotation of the crankshaft, so nothign to do with the pulley.
Once the head is on the engine, the bolts are tightened, in sequence, to 30Nm. Then each bolt, in sequence, is further tightened 90 degrees of rotation. Then that is repeated, in sequence.
The head gasket should come in a sealed wrapper. Do not open it until ready to fit the head. The gasket is coated with a sealer, that starts to harden in air. If already unwrapped, it is scrap. Fitting it will cause early failure, and having to do the job again.
When ready to fit the head, ensure everything is nearby, and ready, and that you are sure of the correct fit of the gasket. Some have been fitted upside down, blocking the oil feed to the camshaft.
Once sure, unwrap the gasket, place it on the engine, and immediately lower the head onto it. Without delay, fit the bolts and torque to 30Nm. Then follow the rest of the procedure. No need to hurry, but no unnecessary delays.