i am a little late to dinner but i have
changed a head before... and
the only pin i messed with was the top one..

the bottom pin was in the block and the top pin was
in the head...leave the bottom pin alone...

we are talking about the drivers side ....
if so just slide the timing chain over it and be done..

the only reason you remove the top pin is to assist in the removal
of the head.... you have the little plastic guide as the sole connection of the
head and everyone attempts not to brake the guide by pulling the
top pin... but you can leave both pins in... break the guide remove
the head and then just slide the guide back onto both pins.... as long
as the cover has been removed...