There are too many things you need to do when installing a head, that are not obvious, that if not done you may trash your heads or your engine.

I would recomend getting a service manual and follow step by step.

Search this site for "head" and read. There are many sad stories here.

It has been my experience to hand sung all the bolts then tighten in 3 stages 1st 55Nm 2nd turn all bolts in order 90 degrees, 3rd another 90 degrees, according to book.
You should also measure your bolts I would replace with new as they stretch and may break if you use the old ones.
good luck.