AJ, you can stop typing now because the Passon 18 spline OD is the answer! 2.66:1, 1.59:1, 1.00:1, .80:1 OD. 18 spline! Fits in a regular case!
Comes in 'kit' form for just under $2k or as a built unit for just under $3,200. Pricey? Yes. Solves problems with crummy factory design? Worth every penny. Slap it into your existing case and be done with bad gear spreads while keeping overdrive.
There's also his 5 speed deal but that's *ahem* a little more coin. He's also not at full production yet so people on the list are still waiting for units. The 5 speed is probably not for me but I'm thinking hard about the kit, just might be my ticket.