It really depends on if they are "stretch" bolts, those are supposed to
always get replaced, but I have never replaced the 1.6L bolts.
You can check the old bolts for stretch be using a caliper, get the
new speck for length, and check all of the bolts, any that are too
long should be replaced with new ones.
I think the more important thing is to make sure the block's bolt
holes are clean and a little oil, chase them with a tap if you have
any doubts, and make sure the bolts have clean threads, a wire
wheel on a bench grinder is great for this, make sure there is oil
on the threads and the washer that the head rides on, to get the
most accurate torque, follow the recommended torque pattern
and recheck the torque after the engine is run for a day or so.
Torque on a bolt is stretching it, like if it were a rubber band, and
it's trying to return to it's original length, too much and it will stretch
beyond it's design and weaken, which is why you measure them,
and too low there is not enough clamping force to keep the
gasket sealed
My $0.02
Wild
