These look pretty cool, but they will unfortunately be too big for Spiders. You are using a T6 model to represent a T3 one.
These actually remind me of some 'count as' Tau Crisis suits I converted in the past:
http://glennsgwmodels.blogspot.com/2014/02/ Using them as T4 models with 2 wounds made sense as they are roughly as durable as a 1W T6 model.
If you really want to make an all Wraith army (which is a cool idea,
btw) I'd suggest looking as the Necron model range. You can easily add little bits of green stuff for knee armour and other additions to make them look more "Eldar", yet the smaller size of the models will fit better as T3 Eldar with good armour.
For example, I would take Necron Warriors with Death mark back torsos as a Warp jump generator and an Eldar gun.
Check the Warriors here in the front:
And for the gun and Warp jump generator, you can use Star cannon barrels and Necron Deathmark torso halves:
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