As you can see, the proportioning valve doesn’t look like it will fit in the place where the bracket wants it to. I cannot move to the other side. As far as I can see, I need to modify the bracket so as to put the valve under the master cylinder. Does anyone have any ideas?

 

Stock Olds location is down on the side of the frame rail and stock-style replacement lines will run down to there. Even then it's common to have to move it to the top of the frame to clear headers.
Underneath the master is the next most common aftermarket mounting point. You can probably find a bracket if you don't want to make/modify one. The generic kits take a more Chevy-centric approach with the valve up high.

 

YMM would help us point you in the right direction, but I ordered the bracket for my '72 Supreme from ILT. Worked like a champ.

 

This is how I have it mounted on my 66

 

The chassis mount spot was where I found the original distribution box. When I tried to locate the proportioning valve there, the starter cable was in the way. So, I would have to fabricate something to move the cable out of the way. I thought it would be easier to move the proportioning valve. Not sure about that now.

 

I saw the bracket that holds the valve on its side under the valve last night. Thank you for the photos showing how it would work. I think that might be the way to go. The downside is that I have several pre-bent lines which might not work.

 

The lesson-learned here is never expect aftermarket parts to fit correctly, unfortunately.

 

The parts have arrived, now onto the brake lines.

 

The front brake lines are installed. You can see that this is the first time I have done this.