The length measurement is taken from the end of the bolt up to the seating surface below the head. I think you may have been measuring the overall length including the head & flange of the bolt. It's unlikely that your original bolts are out of spec (longer than 108, if measured as above), but as we said, it's a good idea to use new ones.

Yes, the torque process should be:
- Be sure bolts are clean and oiled. Oil the contact surface under the bolt head and on the cylinder head surface. Clean the bolt holes of course.
- start with the middle bolts (lower, then upper) and work forward and back equally to the front and rear bolts
- 1st pass approx 35 NM (just to be safe).
- 2nd pass 70 NM
- 3rd pass - 1/4 turn (90 degrees) Use an 18 inch breakover bar.
- 4th pass - another 1/4 turn. (grunt).

That last pass will scare you, they get hard to turn.
If anything acts strange, like not torqueing evenly, you may be galling the surface of the head. Stop, remove the bolt and check.
Some like to use an angle guage, to accurately get the 1/4 turn, but if you very carefully align your wrench handle you can approximate 1/4 turn very closely.

cheers,
DG