Dom...
Those pulley or
sheeve blocks you show in your image 4417 appear as 2 fall [2:1] and 3 fall [3:1] were I believe
wooden pulleys in steel hoops
So as difficult as it may sound, the pulley rings would be
wooden coloured with contrasting paint on the externals........possibly the same colour as the chimney
This then begs the question of the davit posts?........they too could have been the same chimney colour
The examples
sheeve blocks you show appear to be electroless nickle plated which is extremely difficult to remove, or get any chemical or paint to adhere to the surface
Wooden pulley disks can be purchased or manufactured, brass strip could be used to form the hoop
Only way to establish actuals for the period & type of vessel life boats is research
PS......if the davit arms were the same colour as the chimney, then mast/flag pole just aft of the auxiliary ships wheel would also be the same chimney colour
Derek