The Inspector wrote:
I completely agree,...
Good oh.
The Inspector wrote:
...but in spite of building 36000+ airframes, it seems like it's easier to locate a running Maybach for the LZ-29 than a Mikulin,...
Indeed. But see above...
The Inspector wrote:
...plus the Indiana tractor motor sounds more like what you might expect from ground attack aircraft deep and guttural.

And that's the
other crux of the point. 'What you might expect' is remarkably often
just wrong. Fact is, you and I and everyone under about 50 has
no real idea of what an Il-2 really sounds like - we've never heard one, and this great restoration may sound roughly accurate, but may also not.
One of the key points or authentically restoring aircraft to fly is to be able to revive, to some degree, what they were actually like; and like a fixed radial in a W.W.I era rotary-powered machine, it might be a fun way to go fly, but it ain't authentic.
But of course, it's a lot more complicated than that. Actually a lot of what a W.W.II era aircraft sounds like is to do with peripherals and airframe, rather than the actual engine itself, remarkably enough. If you've ever heard a pair of Mustangs, one with gun ports, one without, you'll notice only one has a whistle. Most of the engine noise we hear from the ground is actually exhaust; so a Merlin with three-stub exhausts vs a Merlin with six has a completely different sound (the three stub is much deeper, more of a bass note). There's no Merlin flying with a long tube or shrouded exhaust, as Mosquitoes or Lancasters flew; but the difference between the straight out ports on the Hawker biplane RR Kestrels flying in the UK is a world different to the much more muted sound off the long-pipe car style exhaust on the Hawker Demon. Prop, supercharger, ducting (or not) reduction gear or contraprop gear all have an element to an aircraft's sound. Unsurprisingly, a Hispano Buchon with a Merlin sounds completely different to a 109E or G. So...
...the probability is this sounds about 'right' - the prop configuration, exhaust setup, cowl and aircraft's configuration (ports etc.) all are the same or near enough original. And that's great.
But we don't KNOW.
Regards,