In reality Castrol R 10W60 is an oil very suited to racing.
In fact many people, who race cars, fill their oil sponsers containers with Castrol R 10W60 eek!
So Castrol R 10W60 will definitely be excellent in a road car.
I have used it for years and have not been disapointed.
In fact any Synthetic of 10W40 to 10W60 will be excellent in you Alfa as synthetic oils have a higher heat tolerance than a conventional oil.
ex for a 20W50 oil, the max operating temperature is
1) 110-120C for a good to top quality mineral oil
2) 150 + for a competition synthetic such as Castrol R.
This is the reason I use Castrol R as in very hot weather , with A/C on, the oil will definitely protect the engine.
Over kill, very likely but oil is cheap compared to an engine rebuild
The proviso on the 10W (W=Winter) lower rating is that it is suitable for your climate. i.e. very cold climates may need a lower viscosity starting oil in Winter.