whats the best way to clean up these heads

They have been in the weather after being acid bathed and are covered in surface rust

Well the sides and all that really need more bathing but if its nothing special just use a narrow wire wire cup brush on the end of a drill to clean up the 3 faces of the heads, good as new

Steel wool and some wd40 also works well.

I usually put RANEX in a trigger spray bottle. Give them a squirt all over and allow about 2 hours and wash off with water. Mask up all the parts you you don't want painted and spay with an etch primer followed by your favourite colour. Unmask and clean up the remainding surfaces with steel wool and CRC. The whole lot should be over an 3-4 hours.....

Steve