[LMH]

Accurate reproduction 427 seats are actually quite comfortable IMO. They need to have the rubber spring thingy on the bottom for some flex to the cushion. KMS makes a nice seat, more comfortable than an original seat I think. Pricey though.
I have Sube Cobra seats in my Hurricane. Less money than KMS and pretty comfortable as they have a rubber thingy under the cushion. The base cushion is a little long compared to original's but gives better support. They have a little more roundness to the back which gives you more side bolster. If you knew someone local who had them, you could try them out. I know some of the FFR guys use them.
Larry