Really, as long as they are long enough, worry more about flight quality than length. The back of the point doesn't HAVE to dang near or touch your hand at full draw. It's okay to have a bit of arrow sticking out in front of the bow.
As far as weight goes, at 64 pounds you can easily handle a 640ish grain arrow. A general starting point is ten grains per pound. I typically go over that a bit. Main thing though is to get it tuned well so that the flight is good. A longer arrow will need stiffer spine, all else being equal, while a shorter arrow will need weaker spine. At 64 pounds and a 29 inch draw, you'll need to start with at least 70ish spine shafts, and probably more if you have a very heavy point at all. Again, general rule. Nothing set in stone here. Different things work for different folks.