Looking at the 1959 SI article by Bobby Jones posted recently, here are some of the drastic changes:
1. Tea Olive - 400 yards then, 455 now (Tiger recently said it is the hardest opening hole in golf).
7. Pampas - 365 then, now 450 (as noted, Mickelson said it changed the whole mindset/flow of the round - instead of birdie, it is 2d hardest). (Jones noted how tight the drive was, but commented that the 2d was normally a steep pitch requiring precise judgment.)
10. Camellia - 470 to 495
11. White Dogwood - 445 to 505 (note in '59 Jones said the tee shot was blind in that you couldn't see your ball land, and he said the 2d shot is usually played with a 3 iron or stronger club. Before the lengthening, Tiger said he hit driver, wedge).
17. Nandina - 400, now 440
18. Holly - 420 yards to 465.