I put Lotus Elise shells in my 89 SE. I absolutely love them. They fit me perfectly and give more leg, head, and seat travel room. Also several pounds lighter!
However, they will only work if you are average in size.
The Elise shells were from a wrecked car and needed a recover so I added an extra 1/2" of foam over the stock.
Haven't sat in the Sparco seats, but did consider in past.
Shady, Travis(Vulcan Grey) posted a picture of his interior with Elise seats a couple days ago on the Elise steering wheel swap thread. I will try to post pic of mine. I actually have an extra set, but I am not ready to sell yet.
I'm 6'2" with very long legs, short torso, so I needed more room for my legs. The Elsie seats are so thing that I now fit much more comfortably, and I can wear a helmet in the car without touching the roof panel.
The Esprit seat belt would have crushed my hip bones, so I also bought Elise seat belt receptacles and bolted them to the seat as in the Elise.
And I had to make a spacer for the other side to attach the seat to the frame.