All manual Eagles use the same pedals. An Iron Duke 4 cylinder Spirit will also use the same pedals and hydraulic system. The master cylinder and slave cylinder are also the same, except for the difference in length of the pushrod. Remember to get the clutch resevoir from your donor if it has one.
I used my pedals and hydraulic system from a 258 T5 in a 151 SR4 Eagle just by pulling the pushrod out and swapping it. It is a solid metal rod that just pushes into the boot.
A manual Gremlin, Spirit, or Hornet will usually be a manual clutch system instead of a hydraulic one. You can easily use those pedals but not the whole system. That manual system cannot work in an Eagle because the front drivehaft would hit it. It also was meant to have enough throw for a 9" clutch plate, which I found wasn't enough when using it with a 10" clutch on my Spirit GT. The pedals are the same except that the pin is lower. You must make your own pin in order to use it. That isn't a big deal when you consider that the majority of Eagle pedals have broken pins already.
No matter what pedal you get, make sure you fix the pin.
Here on the forums several of us have had to repair our Eagle pins already. My favorite repair was Shaggimo's, who drilled two holes and bolted a new chunk of metal with a piece of threaded rod on it right to the side of the pedal.
Another member used Jeep Cherokee pedals. It's pretty easy to adapt them. First you need to shorten the length of the tube at the top. The tube works in an Eagle once you cut off about an inch or so. Then you need to put it in a vice and bend the pedal slightly. Then you bolt on a pin just like you would with a damaged Eagle pedal or donated Spirit pedal.