If you updated an early 172?

@A_A I think this was on a shake down cruise – one up, and not full fuel, the 180HP SP might get to FL170.

@Peter 20 hours plus is nothing, a 172 was flown nonstop over Las Vegas for nearly two months!

http://www.countyairports.org/History/History_LongestFlight.html

The old POH show a 155 fpm climb at 2000 lbs, ISA and 15,000 feet, so arguably a 172SP might achieve a bit better than 200 fpm in similar conditions – so you could spend a good fifteen minutes trying to nurse her up to 17,000 feet from 15,000 feet, assuming very calm conditions.

…ISA -15oC at FL170 is roughly a density altitude of FL150.

Am slowly narrowing down the search and while the Continental O-300D engine is much beloved by owner/operators for its smoothness, the Lycoming E2D variant is preferred by owner/fleet managers. Also an alternator is preferred to a generator. Pity as the 172E has the Johnson bar manual flaps preferred by some.

I am also trawling through the NTSB, and 4 out of the 6 carb/induction icing accidents, only 3 resulting in minor injuries in the subsequent forced landing, were O-300D engines. This is over the last ten years. The other two were an M and N variant.

Small fleet/maintenance owners prefer the 172, but some clubs prefer the Warrior – however Warriors under 10-15,000 hours are thin on the ground, while there are quite a few 172 under 5-6,000 hours.