Finally got the floor rebuilt to the point of getting serious about how these seats are going to fit. I got the pair for $22 on sale day at the junkyard, but then dropped about $1300 to get them re-skinned in leather, which I didn't think was too bad of a deal. The low back seats had me freaking out about whiplash protection from getting hit in the ass by a texting driver. Anyway, here's what I did. Hope it's helpful to somebody.
Junkyard seats $22
Old seats/New seats
Now just to make them fit. Started with a piece of 2'x2' 3/16" steel plate. Man I wish I had a plasma cutter.
Driver side
Passenger side
POR15'd
Brackets original to the 99 seats get bolted to the adapter.
Seat belt gets bolted to this. Original floor is sandwiched between this and the 3/16" plate.
I decided not to make the new passenger seat tilt forward. After quite a few test fits it looks like when the new seat back is folded forward and the seat is slid all the way forward it provides almost as much room as the original gave when it was tilted forward.