I'd need help with the balance (CoG) since the nose would be about
70lb lighter (based on engine weight alone, not sure about mounts).

Would have thought performance would be similar with Jabiru @170hp and
the Lycoming @ 180hp.


70 lbs is quite a bit difference. Don't be surprised if you have
to move that engine forward for the W&B and to build
a new cowling. Sequoia may not publicly back the idea,
but I wouldn't be surprised if they kept in touch just to see
how it's working. Also everyone involved must remember that
this is an experimental category, so have fun experimenting.
Lou