[gentlemanjak]

I would think you may have a head gasket problem due to anti-freeze loss you mentioned and the milky engine oil. It could be leaking anti-freeze from intake gasket into engine which is a much cheaper option to repair. Valve lifters could be noisey due to the thin oil in engine, depending on the mileage the Blazer has done you may be better off replacing them anyway seeing as he has the inlet manifold off anyway.
If you have a sludge build up on the inside of you oil filler cap, you'd be advised to run a engine flush through the engine before oil change.
Is the engine running smooth, or does it idle rough? Does it overheat at all? Are you still loosing coolant from engine?

I assume this is a V8 engine!!