chsr17

I hope this is the right forum for this but I can't figure this out! I live in Alaska and most of the maps are NAD27 and not new. The magnetic declination at the time was 27e but the current NOAA declination now is 21e. Do I go with the declination from the old map or use the new one when using map and compass. I do have a GPS but I like having the compass and map as back up! Thanks!