Gary,
Interesting topic.... I think alot of areas can deliver truly monster fish, but often the terrain limits how many one can actually get a shot at, or extract from their homes due to foul ground... another factor also being the level of skill and the tackle that is often required to land these fish, is not always used widely in these areas...
I believe the Mozambique coastline holds some truly mammoth GT's... while not there in perhaps the same numbers as places like Seychelles, New Cal, Oman etc, the number of truly massive fish that have been taken along this coastline by land based anglers on livebaits proves there are some massive fish here.... also these areas are often long sandy points, which means that landing a 50 kilo plus fish on a 12ft rod is actually achievable, rather than a pipe dream.... your mention of surf lines in your post is along the lines of these beaches/conditions... Mozambique has alot of estuaries, very large ones, that drain hard on the drop, and fill hard on the push, and create perfect feeding areas for GT's and other gamefish, with very little in the way of structure for them to bust you off...
Further this range up into Tanzania and Kenya, and you have areas that deliver some MONSTER fish....
Case in point, this estimated 65 kilo fish was taken about a month ago on a Halco Roosta Popper, and CTS popping rod off the coast of Tanzania....
I think right now, as is evidenced by the reports from Nick and the Ocean Actrive Crew, and Ed and the No Boundries Oman crew, Southern Oman is delivering the highest number average of giant fish... their recent reports show more 50 kilo plus fish than I've ever read about.... Oman I feel would surely be THE place right now to target giant fish... the fish are there, and more importantly, the knowledge and skill of the guiding outfits to put you onto those fish is there too....