I have personally experienced improved braking and handling from my P4 Pirelli tires as compared to the 165X400 Michelins. Particularly in wet conditions. I consider this "improved safety".
Under what circumstances, dry, wet in a straight line, on a bend, etc. It is never quite as clear cut as that, a tyre selection is a balance of a variety of factors.
How old were the 165R400 tyres that you took off? It is fair to say when you take off a tyre that will be a few years old and fit fresh rubber then you will get better braking, i would suggest particularly in the wet.
Yes modern tyres have moved on, but in association with the cars they are fitted to. which are set up to take advantage of the wider footprints and squarer carcasses etc. and a 2600 Alfa is still the car it was when it was built, unless you start dramatically altering the geometry.
It is fair to say that, the classic tyres that are currently being made by Pirelli and Michelin today, can take advantages of modern manufacturing techniques, and importantly modern rubber compounds, which they do. This means that the small foot print of rubber that is presented to the road on a tyre carcass that is suited to compliment the steering and suspension of the car that it is fitted to, is of the highest standard, considering the balance between wet use, durability, etc. And while doing so we can also make them look right.
I don't know if you have seen this article Classic Porsche Tyres | Longstone Tyres
which is an article written by a German magazine, where they test a selection of classic tyres. Granted it is not the CA67 tread pattern. and the other criticism i have come across of this article, is that they do not use a modern tyre in the comparison. What should be taken from this article it that it is not a comparison, this is classic tyres scoring the points they score in a modern tyre test irrelevant of what other tyres are being tested, the test results are then put in a table for you to compare. So when the Cinturato scores a 1 in dry braking, then that is it. That is as good as you can expect.
When you fit a wider tyre the steering does just get heavier.