According to the demo screen you have 496 tiles, with half of the 12 tiles of Zara's this gives 502 tiles, making 49.61%, so to get 62% you need 125 more tiles (plus or minus 1). The former Khmer cities in the NW corner of your continent give 32 tiles, which leaves 93. Furthermore capitulating Sury gives something like 8 tiles, leaving 85 tiles.
Sugar island is 25 tiles and China is 24 tiles (without the small islands for the coast, which would give you 2 more tiles if you just conquer the current cities on the island). Together this would not give domination.
As Pacal's land is a longwinded island you would need to conquer many more cities to obtain the domination limit (just over half his land), while Monty seems to have a big compact island. I'd capitulate Sury (waiting to conquer him would at most give 10 extra tiles) take sugar island (easy landgrab), and then hit Monty. He's technologically inferior and taking just a few of his cities should be enough. (Do try and find a forested hill to land on though ;-)).
PS I don't think it is worth the trouble to raze the barb city on sugar island and replace it by two new cities. That would just take a lot of effort, while the island's only purpose is giving a few extra tiles, so that you need to conquer one or two less cities from Monty (or if you so decide, Pacal). For this purpose the barb cities are located fine.
at the moment, could be a bit harsh to loose that money when declaring on him.
