Smoking Issue

[6061Apache]

I have a 61 Apache with a stock 283 and a manual trans. It smokes out the exhaust when I coast down a hill, and pushes a little oil out the oil fill tube at the front of the intake manifold. Doesn't smoke at startup, or going down the road, except downhill. The only crankcase vent is the oil fill tube. Would it help my smoking issue if I added breathers to the valve covers, or is my motor just shot? Thanks for any comments.