Go for it Alan!
My car isn't broke but that isn't stopping me from rebuilding the head and changing all of the gaskets on it
Seeing as you're delving in to the block you might as well do the lot and know that you have a fully rebuilt engine that is going to problem free for many years to come.
Bear in mind all of the gaskets, oil seals and belts will set you back in the region of £400 if you go with genuine Volvo.