To brake or not to brake...that is the question

[wxman1]

My 69 C10 P/U runs pretty well for a truck thats 33 yrs old.
The brakes also work...but I really have to stand on them to
stop the truck from 60 mph. Its not unsafe to drive but my brother
seemed to think that I should be locking up the brakes...given
how much pedal pressure I'm using. It equipped with a power brake booster. When I initially press the pedal the brakes really
take hold but I'm having to exert a good deal more pedal pressure to bring it to a full stop. Is this just the way 4 wheel drum brakes work...or is possibly something wrong with the
power boost? There aren't any screech or scrapping sounds
so I'm not down to the rivets. Maybe this is just a matter of
adjusting the drums?

Jim M.