Thank you, Ulric, for your summary of your internet reading. Can I remind you that anyone can put things online as true, whether it is or not and whether they have any qualifications so to do.
I too have seen the claims that "all that was necessary" was to turn the crankshaft and camshafts end-for-end (etc.) without explaining how and why that could have the desired effect.
Here's the crankshaft (albeit the early version) and you can see it's a normal six-throw job with the throws paired symmetrically about the centre main bearing:
Elsewhere I have seen it stated "The V-12 engines required changing only the spark plug firing order in order for the direction of the crankshaft to be reversed" which is quite impossible. (e.g. consider valve events: if it worked you'd have it drawing in charge through the exhaust and exhausting through the intake).
ETA Stanwell's post arrived whilst I was looking for that photo and he's right about that - and much much more!!