I'd do a top end rebuild only, and then only if I needed it. If you dont plan on going all out with the BOMBing, you should be ok with a thicker head gasket and stock pistons. My 91 spent the first 180K or so pulling a 40ft GN flatbed, hauling tractors all over the west and midwest. The pump was turned up as soon as the owner thought it broke in, and he didnt even put a pyro on it. I replaced the head gasket at 255K- drove it for 10K with the blown HG. Didnt know what it was; just made a funny noise under load. ANyway, when I took the head off, it still had the cross hatches in the cylinders. The original turbo got burnt up from too many hot shut downs. 5 of the original injectors were popping within 50psi of each other- odd one popped at 450 or so. I dont think my engine to be an exception, but rather, the rule. These things can take a beating becaus they ARE so heavy duty, and keep going. I fully expect to get a million or more from this engine, provided I dont sell it.
Blue smoke in a diesel is more often a fuel system problem- you'll hardly ever see smoke if it is burning oil. [why do I have a premonition of needing Kevlar pants for that one?] How is your oil level between changes? I wouldnt worry about the oil pressure in the factory gauge, either. Mine barely comes up to the second line at highway speeds, but has 25 psi at warm idle; 70-75 at WOT. The gauge is fed by an electronic sender, $50 from DC; one step above an idiot light.
Now, I'd go with a ported head, strictly form a flow standpoint; it CANT hurt anything. Get an aftermarket cam, HD valve springs, injectors, pump gone through, though I've seen VEs go 500+ with no rebuilds. ATS manifold is a no brainer, along with a bigger turbo (how much bigger depends on your intentions and goals. ) While it may not hurt to check things out, I seriously doubt it needs a pan to head rebuild. These things put out a fraction of their potential, even moderately BOMBed, and will go forever. 10K hours, at an average of 40 mph, is 400K; at 60 mph is 600K.
Daniel