RV-9A's wing with Rotax 914?

Looking at RV-9A's specification (weight, engine, etc.), I think a
Rotax 914 can power it very well, may give a better performance than
O-235. However, the problem is Rotax is far to light to be installed
on RV-9A.

So I just can't help thinking, well, why not a new design around
RV-9A's wing and Rotax 914. The design will be pretty much on
fuselage. The benefits of this designe of new fuselage+RV-9A
wing+Rotax 914 should be:

1) the basic empty weight should be 100-150 lbs lighter than RV-9A.
Rotax 914's wet installation weight is about 80 lbs lighter than
O-235. There should be more or less some structural weight saving from
the lighter engine installation and lighter gross weight.

2)Rotax 914 has constant 100 hp output up to 12,000 feet so it gives
more horsepower at 8000 feet than O-235.

3)The fuselage, if built in composite, can be sleeker(not necessarily
much lighter though)

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.

Shin Gou