A little insight i found out there.
Ok, here's the skinny (pun intended). If (and this is a BIG IF) you wish to mix radial and bias ply tires, NEVER put the bias on the rear. It doesn't matter if the car is front, rear or all wheel drive.
The reason is a tire quality known as "progressivity." Progessivity is a tendency the tire has to lose adhesion to the road while under cornering loads. The more progressive a tire is, the more you will "feel" it start to slip, (understeer if on front, oversteer if on rear) before it actually loses traction. If a tire has little progressivity, it will slip with little indication to the driver whereas a tire with a lot of progressivity will give indications it is losing traction progressively rather than suddenly. Why is this important? Radial tires, by nature, have a LOT of progressivity. You can "feel" when they are about to lose traction better than bias. It is better, in street conditions, to have a bit of understeer (so you can feel the front getting loose and let off the gas) rather than have the rear end come around during a corner. For most drivers, it is easier to control the front of the car than the rear.
For this reason, when I sold tires, we were strictly forbidden to put bias ply tires (snow tread or otherwise) on the rear of a car that had radial front tires. We were also not allowed to put a lower speed rating on the rear than on the front and we were also barred from putting a higher aspect ratio tire (70 series vs. 50 series, for example) on the rear of car.
In my opinion, Radial front tires on the front of a car with drag radials are THE way to go. First, you are going to have less rolling resistance than a bias ply tire and second, you will have better handling, should you need it.