Drum brakes work pretty good on a 8-9k pound f-350. I bet they will work lots better on your 6-7k truck. Seriously you can buy alot of brake pads for 4-5 hundred bones. Also, lots of people bitch about how crappy the e-brake on the eldorado calipers works.

I'm sure you know this as well, but you might end up needing to get a new/ adjustable proportioning valve as well.