As an FYI: The new Rubie's pack appears to be the Spirit pack, repackaged. It's on Amazon, ships free with Prime, and only costs $51 there vs. Spirit's $69.99. People have commented that the Rubie's PKE is identical to the Spirit PKE, but has crappier quality wiring. The same may be the case here, but that won't matter because you're using Spongeface's kit anyway, and gutting the existing wiring, I imagine.
Also helpful to know: Spirit is ALSO Spencer's Gifts, and they sell the proton pack online as well -- so if you decide to just get another pack and keep the second one for a next project or to sell to someone who wants to do a pack with a non-spirit wand, you can coupon hunt online for both Spencers and Spirit coupons.