No plate at the firewall, unless you're adapting the late master cylinder. No pushrod on power brakes, the offset linkage bolts directly to the pedal- the booster has a rod that pushes the master cylinder.
So, since you are removing the booster (and linkage) you need a pushrod. #4.
So on the 74 duster I have with the power booster once I removed that I don't need the big steel plate like was on my 66 satellite behind the manual master cylinder?