Rear brake pedal will not move

Hello,  Wondering if anyone has any advice...

I have 1976 KZ750 B Twin.  Rear brake pedal will not move.  
I thought is was the rear master cylinder that was frozen. Removed it, and the cylinder seems to be in proper working order.
Still no movement on the pedal. Could kind of move it, when hitting it with an 8 lb hammer...  Could not get the pedal off.
Any ideas on how to remove / loosen or replace?

Thanks.
 

Seizing of the pivot is not unusual if maintenance is neglected in the way of greasing the pivot shaft.  Have you tried soaking the pivot point in PB Blaster or similar? 

trying to,  but so far, no luck...  
 

Some heat on the break pedal sleeve will expand and should break the rust locked pivot shaft.
Sometimes you need several heat and cooling cycles to unlock the parts.

been trying acetelyne as well as the PB blaster,  almost having it move,  but not enough to be an actual break....
 

Be patient and persistent. Regular application of penetrant over several days may be required to get the penetrant well penetrated. Then some heat and tapping. May need to repeat a time or two. 
Keep in mind that heat will cause the penetrant to evaporate, so reapplication when it cools down will be necessary.
 

Lean that bike over as far to the left! Let it sit for days! So penetrant can get down that tight, corroded, 2” x 18mm shaft! Lot of territory to work!

Looks like there's enough room to fit a grease zirk to that pivot tube...

I'm fighting this right now on a 77 KZ750B. But my master cylinder is complete toast, the piston is hard frozen.  I've gotten in to move a little with heat. Now letting penetrant soak. Luckily my caliper is not frozen too. Looks like I can make about any 15-16mm rear master work for me since I'm doing a custom.

That's common on these bikes that never saw grease on that pivot, then set up in wet storage areas. They can be a real bastard sometimes. If all the penetrating lube in the world and heat doesn't break it free, you can split it with a thin kerf abrasive cut off wheel enough to open it up to get some lube on it. If you can't find a replacement pedal, it can be carefully welded and refitted to the pivot shaft. One of the things we do for these bikes.