5gr/lb, just what Dave said. Actually, for turkey penetration isn't an issue. Most experienced turkey hunters advocate not getting a passthrough, saying that if the arrow stays in the bird it impedes their ability to fly off.

3D? Those things don't care how far the arrow goes in. Actually shallower is better.

Although you don't give a length at 55# you could probably shoot a GT Ultralite 500 is around 27". Longer and you might like the Ultralite 400.

I use the UL 500 at 27" and 53#, but with either 80 grain Nibbs or insert and 65 grain screw-ins. This is not my hunting arrow. They weigh 267 grains. Would I hunt turkey with them? In a minute.