We had one of those in Ohio. It's not silver/woodgrain/blue interior & a 400, is it?
As shown on H-H, big car = big tires & your OPTIONS are getting pretty slim. If you still want a whitewall - I think the only thing out there is a Hankook 225/75/15 at 28.3" tall. With RWL there's always Radial T/As in 255/70/15 that are 29.1" tall. Lots of SUV outline white letter choices, but most are truck tires.
What are your plans as far as wheels/tires? A HR78-15 was ~28.8" tall.
Here's a 40 year old one on eBay.