Try raising the truck and going at it from the bottom. If that plug is rusted through (as it seems) the lag screw/pry bar method might or might not work. That is to say I've had those which didn't have enough metal left in them to let me get them out that way. But if you're patient and resourceful, you'll get it. As for a Carter carburetor, I don't currently have what you'll need, however if you will send me a PM I can mention some other ideas.
