Seems like everything should be fine the way it is as far as SG goes, unless of course you want a lower ABV when your done, in which case you would want to water things down a bit. At its current SG I think it would yield a little north of 13%. Although many on here have a far better understanding than I. I'm sure someone will chime in with greater detail soon.
If you are concerned about the yeast reacting to all that sugar, go with a yeast starter and once the yeast is hydrated and happy, add in some of the must. Once acclimated to the diluted must, add to the fermenter. You should do fine.