Yes I did consider the tip weight to the spine when I bought the arrows. Thats is why I was confused with straightarrows post about all those relations to arrow length. Thanks for clearing that up.
The spine ranges given by manufacturers are just approximates. The actual ideal dynamic spine occurs at only one length with any particular bow setup. Simply cutting your arrow so it goes 2" past your rest will not acheive this. However, you're welcome to follow whatever advise you want.