If you decide to go external oiling, here's what I use. I don't see why it would be a problem using it in an A body. Maybe just route the line differently.
It's a Milodon pump w/ a stock cast iron cover. I like these b/c the pickup is in the pump, higher up, and not on the cover. The pan is from 440 source.
The way the line is, it goes b/t the engine and K frame...no need to disconnect it to remove the engine from the car.