Wire it according to the simple PSC plan.
You do have a start capacitor taken out by the resistor on top of the black start capacitor.
The SSPE will take out the start capacitor electronically with a timer (built in) as well as taking itself out once the compressor output voltage returns to normal after start up.
"Normal" voltage is around 130 volts across the run capacitor. At start up, there would be no volts, before it is started, and then jumps to above input voltage once it is running. This is the reason a run capacitor enhances the torque on the compressor, as it will have higher voltage across the terminals because it is there.
If they are recommending removing the stock start capacitor while adding the SPPE, then remove the black capacitor, and it's white and red wires. The SPPE 6 has a built in capacitor in the 100 - 130 mfd size range.
I found the link to the SPPE capacitor size here.
http://www.supco.com/web/supco_live/products/SPP6.html They make a SPPE4 for 120 volt compressors, and SPPE7 that has a slightly higher MFD rating.
Good luck,
Fred.