Tim,
I am not a brake expert by any stretch but since no one else has answered your post I will try to get you started. First off is your proportoning valve adjustable from the cockpit ? In other words do you have a small knob that you can turn or do you have to do it with a wrench or screwdriver ? You are correct about wanting the front brakes to have more bias. If you have a parking lot you can test in, set it whichever way it will give you a little more front bias. The papers that came with the valve should tell you which way does what. Drums don't take as much pressure as Disks so you won't need as much in the back. Set the valve and then drive the car slowly and step on the brakes to see how much front brake you have and just go from there until you get it the way you like it.
Ron
