Ok, I have a set of 3 Kevlar/Teflon FA84 brake pads, they guy who I bought the 300ex from gave me.

In trying to put the new pads on, It was a complete bitch for the one side,
and Un doable for the other side.

The pins wont go thru, I can start to tighten one or the other, but once
one pin catches thread, the other wont catch.
You can look thru from the back, and see that the pins looks slightly uneven.

Now, the pins look a little scuffed up and whatnot, but they appear to be straght.

Do I have the right pads, or Do I need new pins?

 

Hmm, well I saw there was a plate inside the caliper that flex'd a bit, so I had a buddy put pressure on the bottoms of the pads, and
I got one thread started, than used a c clamp t put pressure on the hex key in the other, turned it, they both caught and went in fine after that