Use the 3555's but I would advise against cutting them and then trying to tune.If at all possible start full length with your insert glued in and fletch a couple and leave a couple bareshaft.Use the planing method on OL's site and tune the arrows by length.Just trim from the nock end 1/4" to 1/2" at a time.
You may need to remove feathers and cut the shafts down if they show weak but the price of a few feathers is cheaper than a whole dozen shafts that have become too stiff by cutting too much to start.
You can probably tune at 29" but you may have to go with a much heavier head than you intended.A lot depends on your release,the bow,ammount of center shot,string,silencer material,even form.
PS
once you find the correct length,you will get the straightest shaft by triming the same from both ends.On carbon shafts the run out is on the ends and determines the straightness.