well as u got ur engine-head opened, see the valves, if they r a little weak/jammed, get them replaced in da same go.
for heating case,
you must consider that your block etc are properly faced otherwise gaskit wont survive long(i have suffered on ma cultus).
dont let the mechanic put double gaskit, ask him get the surfaces faced and put single genuine gaskit. Usually mechanic dont get it properly faced and try to cover it using double gaskit