Attack of the coil killer!

10.8 is a little high for a street car. Not excessive, but high. The position of the coil should make little difference. If they are leaking, they are defective. Remember, factory coils on a few million mopars lived fine on the engine, on their side. I use MSD BlasterII coils for 90% of my stuff. I have not had any that failed, and none leaked. And, they seem to be stable to way past 6500rpm. I would recommend replacing the ballast resistor and check the voltage again. If you can get it down to 9, you should have no issues with any coil.