The rear legs of Golf/Jetta seats will need a little modification.  They set about an inch too wide and if I remember correctly they are a little too short.  A friend of mine put some 86 Golf seats in his 75 Beetle and they worked well after he modified the legs . . . however, they were a little too high for me (He's a little feller, so he fit just fine.  My big belly didn't want to clear the steering wheel).  If you removed the center "hump" that the center track rides on from the Golf or Jetta and put it in the Beetle, it might sit at a better level.  At any rate, ANY seat replacement you come up with for 73-75 seats is going to be better than what's in there.  Those have to be the worse seats to ever leave Germany in a vehicle of ANY kind!