[old ugly]

those 2 bolts that hold down the water neck can crack the ears on the neck when tightened down. be careful. they may have been left a bit loose so as to not damage that neck.
if sealant does not work you could remove the neck clean the maiting surfaces and put it back on with just a good gasket maker/sealer.
but if the leak is at the head gasket and the sealer does not work then it may involve a new head gasket. i would try to avoid that if it is running good and the leak is not too bad