Start the car and let it warm up,once warm adjust the idle mixture screw in(clockwise) untill you notice a slight stumble,then back it out(counter clockwise) till it smooths(about 1/4-1/2 turn) But if its running that rich,you may have wayy too much jet. Try to adjust it first,clean your plugs and go for a drive. Then check your plugs after and report back. I bet you have a 61 jet,and should be at 57-58-59 ish.
As far as timing, somewhere between 8-12* is usually what the slant likes. Keep bumping it up and test driving it till you find what the car seems "happy" with. I bet 12* will be it. I had a 67 Dart and it liked 16*,but then my 70 liked 10*.
