"Peter Dohm" wrote

However, you will also be changing the area and arm relationships of the
side view of the aircraft (there is a name for this which I cannot recall)
and the size of the verticall fin will need to be increased if you are to
retain the same yaw stability. Then, because of the increased area of the
vertical stabilizer, a larger rudder would be needed to retain the
original
crosswind landing capability. In addition, due to the increased planform
area forward of the CG, a larger horizontal stabilizer may well be
required
to prevent any sort of deep stall or flat spin tendency. Finally, just as
a
larger vertival stabilizer requires a larger rudder, a larger horizontal
stabilizer will very likely require a larger elevator.

To put it another way: Engineering is the science of compromise, and an
airplane is a series of compromises flying in close formation.

It should not change all that much, I'll bet. If you look at that heavy
engine moving a few inches, and the increased cowl area in front of
aerodynamic center pressure, then look at that long, long arm back to the
fin and rudder, it should only take about a third of the area the engine
added to make it all work out. Increase the fin/rudder height a couple
inches, or add a small dorsal fin, and all will be well in the world. :-

Reminder: all usenet advice is worth what you pay for the advise.

To the OP; what are you using that is 100 lbs lighter, and what was the
original? That is a nice weight savings!
--
Jim in NC