GW colour details - the only item within the cab that was painted red was the regulator lever, nothing else, and it was Venetian Red (aka red oxide) not bright red. Inside the main frames between fire box and smoke box, including motion bracket and other cross members was also Venetian Red. Cross heads, being cast iron, were painted black so there is no need to try to match the connecting rod. All non-wearing surfaces of the cross head guides and supports were also painted black. Buffer planks and housings were painted China (Chinese) Red, not vermilion. China Red is quite a dull colour but its main advantage is that it covers in one coat over a light grey or red oxide undercoat. I make it from equal parts of Humbrol Bright Red (21), Humbrol Tan (9) and LMS Crimson Lake (or Humbrol Maroon). The buffer shanks and back of the heads were painted black.
For rods which aren’t going to be weathered I thoroughly clean them with a fibreglass brush and then rub them with a cotton bud soaked in chemical blacking. Once dark enough and dry I very gently pull the fb brush over them at an angle until the rods take on a steel-like sheen. For brass brightwork I paint with very dilute black which dulls the brass to a more realistic sheen but also settles in the valleys to emphasise the relief. I leave bright copper unvarnished to tarnish naturally.
I hope this is useful.
(When does Hercules get its numbers?)
Ian R