Transaxle wear can be easily eliminated by simply using the Audi Transaxle
with its
V-8!  Rotating the transaxle 180 degrees and flipping the ring and pinion
to the other side
is commonly done on many Porsche and VW transaxle for rear to midengined
applications
(see 911/915  Transaxle into a 914).

In considering engine conversions, one must pay strict attention to a
Gearboxes TORQUE Rating.

As far as using HorsePower ratings on Transaxles, I understand that to be a
meaningless specification.

Remember:

You can have a High Torque, Low RPM engine (see truck engines) rated as the
same HORSEPOWER
as a Low Torque High RPM engine (see Motorcycle engines).

However, the Transmissions/Transaxles of these units are VERY different
ANIMALS.

A Gear or Mainshaft has no "idea" of what rate it is turning at, it only
"sees" the forces exerted
which is a function of an engines torque and the "reflected" (the actual
load the engine is moving (see vehicle weight))
torque of the vehicle.

Torque/Cubic Inch-Or Liter is an important consideration in comparing the
"performance" of an engine.

Brian