I was about to suggest the Seabring seats as I remember other members have used them in the past. They are cheap and plentiful and still technically a Mopar seat.
I used the stock 68 buckets in mine with new foam, covers and some springs repaired. They look good and are period correct but they SUCK as far as any lateral support goes. Luckily I'm not into the twisties so much, more of a straight line guy.