Swapping front drums to Kelsey Hayes

1969 Swinger 340....
1. I did not know that factory A bodies with Kelsey Hayes systems had a main Porportioning valve and then a secondary proportioning valve 8 inches further back ???
2. Does anybody have photos of a factory GTS setup showing both mountings of proportioning valves on vehicle ?
3. Has anybody done this conversion and what proportioning valve or valves did you use ?
4. Do you need both valves when doing conversion ... is there one p/n that you can use to make system work?
Any info greatly appreciated ...