Not sure this will help but I usually pull the parking brake handle like 5 'clicks', or so, for the shoes to hold the drum while I try to turn it by hand.  Then release the brake handle all the way and verify the drums turn freely.  This way I felt when I pull the brake handle fully it will hold the car on a hill.  Then I verified that it will hold on a hill, which it usually would.  

Is there an adjustment on the park shoe?

Bullet Bob wrote:

I went through similar issues with our's, Steve.  96 Explorer rear in the Heap, all new brake stuff.  First, I adjusted the shoes just like I used to adjust drum brakes...tighten the shoes until the rotor is locked then back off five or six clicks.  But I still had a poor park brake even with the cables tight.  I'm using the stock park pull lever but I added a couple of inches to the cable lever under the car.  that gave the system a lot more leverage.  Still no joy.
Last year I tightened the cables more, and then more, and finally, even more.  Now I have a decent park brake with no drag when released.  It seems that system just needs to have that lever moved quite a ways before it actually moves the shoes.   Crappy system IMO.  If I ever get the energy I'll swap to the Mustang rears which use the service pads for park function and work very well, I'm told.
 

   I was thinking the same thing Bob being a crappy system.  If you had to use them in a emergency I dont know if they would stop you.   Ill try some of your tips and hopefully makes it better.   I have the MS brackets and 2019 Mustang rotors and calipers on my 69 rear.  My E brakes work really well.    Thanks for the info!   Steve69