I used some seats from a Honda Delsol. They are a very low seat and the shape and fabric looked good in the car. Roof clearance could be an issue as mine has dropped floors to allow more head room but as long as you aren't flipping them forward they'd be ok. They bolted in with almost no modification and only cost me $50.
Dan

I have a set of early Mazda Miata seats in my '77 GTE and they fit real nice and 3 of the mounting bolts fit exactly where the Puma seats were bolted down on the pan.. Tried a pair of Subaru WRX seats but they were too wide.