E24 clutch problems?

I had a really odd problem with a clutch rebuild I did a while back. I ordered a new master cylinder, usually a pretty routine install, but it was a terrific struggle installing it. I couldn’t get it to fit the mounting bracket. To make matters worse, once I got it mounted, I couldn’t get the clutch pedal properly adjusted. WTH?!?

So I pulled the new part out & compared it to the original part, side by side. You know, that thing you should always do when you get new parts? They looked similar enough at a casual glance, but once I got them side by side the difference was obvious. The new part was slightly shorter, especially in the extension. The bracket mounts were also a few mm off from the mounting lugs on the cylinder. Fittings were the same otherwise.

I never went back to double-checked part numbers, just reinstalled the old one and left it that way. I was very frustrated by the experience, I’m no rookie and this was definitely a noob mistake. My typical auto part supplier doesn’t make mistakes like that, I’m suspecting it might have been me.

Since there really aren’t any clear pics of an E24 clutch pedal setup on the web, at least that I could find, feast your eyes:

This is the stock setup, BTW, not with my incorrect part installed.