The good old Datto 1600 (and yes Andrew they were only known in the US as the 510). But to compare a Datto 1600 to a Berlina is not the right comparison. Against the Giulia and Fiat 124/125 would be more appropriate as Richard commented on.
The thing is, out here in Aus, pretty much every Rally driver from the late 60s to probably early 90s cut their teeth on one of these Dattos and/or later models like the pig awful 180B and 200B (a 180B with 20 more mistakes). They were cheap, used to be in plentiful supply and once modified were very effective club level rally cars. In their day, they were a really successful rally car.
Not too many 1600s Dattos were track raced out here as I recall, say apart from at Bathurst and a few of the other major races around the country.
Neither the Alfa Giulia or Fiat 125 were readily raced or rallied out here, as they were too expensive, European (which meant strange) and generally were considered unreliable. Now of course we know this to be not so, but then we are the cognoscenti.
I remember going for a pretty fast and wild run in a rally prepared Datto 1600 owned by a mate of my brothers and being very impressed with its lightness and handling capabilities. He actually won his class in the State Rally Championship with it. It was a hoot. But while they were tough mechanically, bodily wise they were pretty flimsy.
Of course which would I prefer well the answer is obvious. I must admit, and Richard could testify to this, the 124 and 125 (of which I have owned examples of both in the past), while technically cheaper and perhaps ultimately not as good as the Alfa Giulia or Berlina, were both very competent Italian sports sedans. The 124 being underpowered (although the Special T did get the 1600 twin cam), but with some tweaking they could be made to go. Both handled well.
But yes like our Alfas, boy the Dattos also rusted pretty badly.