RV-9A's wing with Rotax 914?

Shin Gou wrote:

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

No right or wrong from me, but if you're going to all
that time and trouble, why not design a whole new
airframe for the envelope you intend and the performance
you want. RV wings or not, what you propose will almost
certainly take longer and be more expensive than an RV.
I'd also bet that you wouldn't see enough performance benefit
to warrant all the changes strapped to the same RV wing.

Interesting project from an engineering point of view,
but not very practical, IMO.

Dave 'clean sheet' Hyde