1989 Dodge Daytona oil

I just recently purchased a 1989 Dodge daytona ES.
i have replaced the spark plugs, air filter, oil filter, valvecover seal, oil, andput in a new a/c belt needs a new muffler system. Just recently it has started blowing white smoke so I checked my oil and it is brown and a bit sluggish. Notice I said I changed my oil maybe it's my piston rings I don't know I would love to put a whole new engine in it if you have any links to a website where I can get a new engine for this car that would be greatly appreciated so any suggestions to what might be wrong?