73 Plymouth duster ignition

Do you have ANY power? Headlights? dome? Radio/ heater etc when key is on?

What started all this? Why did you change these parts in the beginning?
==============================
You replaced the relay, you said, that's what he's talking about jumpering.

Relay should look like this



The two small "push on" terminals are electrically interchangeable. One goes to the neutral switch on the transmission, the other goes to the "start" signal coming from the key. Those two terminals are the magnetic coil of the relay

The largest stud terminal is a battery junction point and is also one relay contact. The "big square" terminal feeds a wire down to the starter solenoid and is the other contact

You should be able to jumper the two largest exposed terminals and get it to crank

You have a 73?

Auto or stick? Stick cars should have a clutch switch which must be working.

If you jumper the two relay terminals and the engine cranks MAKE SURE IT'S IN NEUTRAL!!

then find out why the relay does not work.

Pull the "push on" terminals loose and one wire is normally yellow. IF not put your meter or test light on first one, then the other wire. Twist the key to start. One of those two wires should be "hot" when key is in "start"

Put that wire back on the relay.

Take an alligator clip and ground the remaining terminal. Try the key, does it crank?

If so, you have neutral switch problems or transmission linkage. With neutral switch hooked up "as normal" hold key to start and work shifter from park to neutral and back. Listen for cranking or a "click"

NONE OF THAT works?

You might have a defective relay. To find out, take an alligator clip lead and ground either of the "push on" terminals. Take a second clip lead or a screwdriver and jumper the remaining "push on" terminal to the large battery stud. You should hear the relay click or the starter should crank. If not, and if you did this correctly, the relay is bad