I think the filter pots could be original - these Bourns pots were used for a short time, but the aluminum rivets would shear off if you hit the knob hard enough, as seen in the photo. It still works OK usually.
I have my doubts as to Burl Amboyna for the top. Granted, the photos are not entirely descriptive, but I would wager the top is either Maple or Myrtle, with what looks like a cluster burl in the images provided. Keep in mind this finish has yellowed quite deeply, so the color is not a clue.
Also, a 1977 would have a satin finish, so the dullness is expected - and a few slightly shinier areas from use if it got some.
As Gregory noted, differing tops and backs (and peghead veneers for that matter) were actually quite the norm for this time.