E9X booster into an E30 clevis question.

[Turbo30]

I need to replace the stock brake booster with a smaller diameter one so that I can make some space for a downpipe. All my searching led me to consider an E9x brake booster swap, but in my research, it seems like everyone talks about needing a customer clevis pin and modifying welding the rod end to make it work. Visually, I don't understand why this is the case, so i bought an extra e30 pedal assembly and the e9x brake booster to mock up outside of the car. Surprisingly, everything lined up.

Looking at the attached picture of the mock up, why is it a bad idea to just throw a couple of washers on either side of the clevis pin and call it a day? What am I missing?

[Northern]

I think it's that the pedal is too high (or low? I don't remember which) and there's no adjustability.

[reelizmpro]

Maybe because that's not the E30 pin? Maybe you have the E90 pin which surely fits but doesn't have any place for the spring.