Hondo44
Hawkeye
If the hammer cocks fine without binding when the cyl is removed, than you're right, the pawl is a large frame pawl and sightly too tall for the 357 mid size frame. Double check by installing the cyl and placing a credit card under the cyl to keep the latch from rising. If the hammer doesn't bind, it can only be the pawl.
Therefore stone or use a Dremel tool to shorten the top of the pawl (it's too hard to file) a little at a time until the binding goes away. Do that with the pawl in the gun: cock the hammer to extend the pawl all the way up and prop it from behind with a wedge of wood to keep it from moving while you shorten it. Test the cyl often.
After you fix the binding you may need to lower the 2nd step of the pawl as well if the hammer won't cock after the cyl locks up on the latch.
Therefore stone or use a Dremel tool to shorten the top of the pawl (it's too hard to file) a little at a time until the binding goes away. Do that with the pawl in the gun: cock the hammer to extend the pawl all the way up and prop it from behind with a wedge of wood to keep it from moving while you shorten it. Test the cyl often.
After you fix the binding you may need to lower the 2nd step of the pawl as well if the hammer won't cock after the cyl locks up on the latch.