I think the days of 'fragility' of the engine are long gone. The original head gasket wasn't up to the job, but I suspect every S1 out there will have had theirs replaced by now. If you are getting a K series, you need to ensure it has been changed, by whom and replaced with a 'payen' one.
Assuming the Yota engine is the same as in my Celica GT, the 140-90 bhp range 'kicks in' at about 6K revs when the Celica is screaming, so it must be very loud in an Elise, whereas the progression is much more linear in a K Series.
Get a Sport 190 and become part of an exclusive club 😃