valvetrain noise 5.9 magnum

Well this engine is not a high mileage engine, it has around 20 to 25 thousand miles on it. And its always had wix filters and synthetic oil ran thru it and its always had premium fuel ran thru it all its life, And when my old man had it he didnt have a very radical timing curve on it. He ran it at 8 degrees initial and 34 degrees total all in by 2800 to 3000 rpm and with premium fuel.
Since i have gotten it i changed the timing a little bit, i run it at 16 degrees initial and 34 degrees total all in by 2800 to 3000 rpm. And i still run premium fuel (91 octane) and wix filters with synthetic oil. It never burns oil upon start up, it was burning oil upon de-acceleration a few months back, but i found out what the issue was. I was running a pcv valve and no breathers on any of the valve covers and i had a vaccum leak at the intake manifold on the drivers side. I added a breather to each valve cover and fixed the intake manifold vaccum leak by installing a new gasket and it hasnt burned oil upon de-acceleration since then. And the compression on each cylinder is 150psi and i am 4000 feet above sea level and my vaccum is steady at idle. It always has good oil pressure, it idles around 20 to 25 and running down the highway it goes up to 50 to 60 psi and it always runs right around 190 to 195. As far as i can see this engine is in good condition, the only thing i have not done to it yet is a leakdown test wich is something i want to do.
But if this issue does turn out to be lifters, would i be better off to get brand new cylinder heads, like iron rams from hughes or eq magnum heads? ones that are more resistant to cracking and putting new lifters in while i'm at it? or would i be better off just putting new lifters in and keeping the heads i have?