American Airlines had 400,000,000 of data collected and ran TBO's several times longer LOP than they or the military could achieve ROP.
If anyone had proof of which you seek they did.
Ah, that old chestnut. It's misleading to claim the old radials are the same as a Lycoming. Sure, they work on the same principles and use similar materials, but so does an aircooled motorcycle engine.
Some things which might be different, which may or may not make a difference:
- combustion chamber shape
- combustion chamber volume
- compression ratio
- valve timing
- ignition timing
- duration of the power stroke
- fuel specifications
- frequency of power changes
- power settings used e.g. maximum range settings
What manifold pressure did they run? Can I run that in an IO360? If not, maybe not all the operating parameters are directly transferable.