Good news. Turns out the dash fits over the transmission without modification. I'll still need to build a center console over it, but that's okay. I knew I'd have to do that.
Then as I was sifting through bins of parts I came across some stock HiLift springs. Wow, these are easy to bend! So I did a little eyeball de-arching and test fit them under the truck.
It's still got a smidge of negative rake, but it's hardly noticeable. I may leave it like this, but I'll have to paint those springs, of course.