Brake Question

So I was going to move around my 72 the other day, and when I hit the brakes it sounded like something kinda broke loose and the pedal got very soft and the brake light came on. Im guessing that maybe one of the stuck wheel cylinders broke free, but in doing so it also looks like it drained the front brake reservoir which Im guessing is why the light came on. Now do I need to do anything besides going through things and bleeding the brakes once Im done? I had already picked up basically everything for the brakes besides the M/C and hard lines. So just wanted to check, as a friend mentioned that a pin in the proportioning valve may have shifted and may need to be moved back. So thought I would check here since it seems like a pretty knowledgeable crew. 

If you have the valve out when you replace everything, you can center the pin by hand. If everything is still connected, fill the front brakes reservoir and then open the line at one of the rear brakes. Apply pressure slowly until the pin centers and the light goes out. Bleed front and back brakes when done.