So, my 88 needs a new tumbler and I need to put a new turn signal cam/switch anyway. On my 5 speed car, it has the little lever to release the key when you turn the car off. I can only assume that is what this little metal bump is circled in green. Can I just buy a new ignition tumbler that doesn't have that bump and I can delete that key release? Basically, I need a new tumbler and not sure which one I need to get.

 

I don't see why not, I went the opposite way (auto to manual key) when I did my 5 speed conversion. It fit fine. If it did it again I would probably not bother, but at the time it seemed like the thing to do.

 

So I pulled mine apart today and installed a tumbler without that little metal notch. The key release lock still functions but now my key buzzer does not.

 

You have not reinstalled the plastic and metal switch correctly for that annoying feature.
check out some diagrams on how that fits in after the lock cyl goes in.