Dismantle-rebuild a certified aircraft

G'Day all.
Just a quick query for all, both in the US and Australia.
If I was to take a proven aircraft, say a C172, totally dismantle it,
including EVERY rivet and bolt, replace anything corroded (ie:sheetmetal
etc) and any hardware/bolts/cables, and rebuildcorrosionproof it, put in a
certified or auto engine, Photograph the entire process to prove you didn't
cheat, could it be certified as an experimental?
My intertepretation for Australia is that is allowable, and as it is a
proven aircraft, you have all the numbers to prove specs from the original
manufacturer. The only thing that would prevent a simple sign-off after
hour would be if you used an auto engine, and I know there are some
successful Cessnas out there with auto conversions in other countries. If
you fill in the paperwork to prove % as per CASA regs you'd be in without a
problem.
For the airframe you can obtain many engine-free fuselages in the states and
basically have a zero-hour remanufactured aircraft for a small % of the cost
of what Cessna/Beechcraft/Piper are charging.
Any thoughts/opinions/evidence/flaming (please minimise this bit).
References would be appreciated.
Thanks in advance.
Rob.
Melbourne Australia.