Just recently replaced my heads, i rebuilt used heads with new valves, springs, seats, seals, o-rings, gaskets, rocker arms, pushrods, and everything has been running fine for me for about 4 weeks.
If the motor is real old, i would think about getting a crate motor.... To check if this motor is real old, check all the manifold bolts, nuts, etc. When I was putting on the rebuilt heads, a few exhaust manifold bolts got stuck in the new heads, b/c i tried reusing them /forums/images/graemlins/doah.gif
So, I would double check if you want to put new heads in, it would be cheaper, and it should solve your (blue=oil) smoke problem.