Nope, sorry, no high capacity magazines. I have heard good things about the 64, some minor bad things also, I have been thinking about picking one up myself, although in no way are they as good as the 10/22, but they do cost half as much and will most likely be a bit more accurate out of the box.
If you want higher capacity the Marlin 60 holds 14 and will be a very nice rifle. Some other models will hold more. The Remington 597 has aftermarket magazines that are 25 rounders.
From what I can tell, 64 owners are happy with the gun. Just buy a few extra 10 rounders and go to it.