Not safe like that. Fixed back seats require 4 or 5 point harnesses. Lap belts need to ride across the lap, not waist.
Stick to reclinable seats and get something with nice covers. The fabric on my Sparco seat has already faded a bit (3 years) and its torn on the left bolster. Considering I only drive the car 15 or 20 times per year, I'm not too pleased with that.
Personally, I would look for nice pair of lightly used STI Recaros.