nomad55 - as far as the front buckets go, that should be fairly easy as long as you have access to a welder to fab up the additional brackets needed for your retrofit. '53 and '54 Chevrolet Sport Coupes (Hardtops) have a good front platform to start from - the back-seat retrofit might turn out to be a can of worms. If you have a good rear seat spring frame, I suggest you think about having it redone to match your front buckets. There are several good upholstery artists out there, who can work miracles with sculpted foam and leather vinyl or fabric.. Due to the tight fitting nature of the hardtop's stock rear seat frame arrangement, you will have to get something that's either dimensionally correct to begin with, or alter it drastically - That proposition could be more costly than most any other alternative.
I went with the convertible interior on my '53 Hardtop, and was very pleased with the results.
Good luck, I'd love to see a picture once you're done with it.