Funny thing with bolts that have been there for 40 years and don't want to come out.
get some pb blaster or liquid wrench and soak those stuck bolts. then give them a nice tap with a hammer to \"shock\" them loose. then get some heat on them. then when they're hot get the socket and rachet on them and slowly loosen them off. carefull tho with the pb blaster/liquid wrench and heat. that stuff is flammable.
if they're hard coming off, turn them off a turn, then back on a half turn, then off a full turn, then back on a half turn. rinse & repeat.
good luck.