Here is Mika Salo's 1999 Ferrari helmet texture for AC.
Install helmet and visor textures to ..steamapps/common/assettocorsa/cars/???/skins/??? folder. Use textures with modern cars, because old cars uses older/different helmet shapes..
Helmet template by Chargingcar. Sorry about mirrored visor, but it's not my fault..
Mika Salo's 1999 Ferrari Helmet 1.0
1999 Ferrari helmet of Mika Salo