I think the Elise seats would probably fit although I wouldn't recommend the S1 variety, they just don't have enough padding !
On the plus side they are both lighter and thinner than the Europa seats so I'd guess there will be more fore & aft adjustment. The sub frames are minimal so you'd need to make something to space them off the floor but again you might grab another inch or two of headroom ?
If anyone is serious about this option I'll measure mine. AFAIK S1 & S2 seats are interchangeable but the ones I'd go for would be the later S1 & S2 seats, again because of better padding where you sit. They really do feel like sitting in a race car fibreglass shell seat, but not one that's molded to fit your backside !