***
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.***
No, actually the motorcycle engine is the different one. Mainly due to the shape of the combustion chamber. All of the above issues are so close between the radial and the flat engine as to be non-issues. The truth is, that the radial is a bit tougher to run… mainly because the detonation margin is narrower than your 360. They both run under very similar ICPs which is the big issue.