+1. I replaced the valve in the oil pan with a new one when I did my cam swap, knowing that I could plug it as well. I was installing a high volume oil pump, so it seemed like extra insurance against oil pressure being too high, etc, but I know now that I needn't have worried, and it's a pop-off style valve anyway. In any case, the new valve will last the life of my engine.
Also, Melling ships many of their pumps with additional springs designed to produce different pressures so you don't have to shim them if you don't want to. I kept the standard (yellow?) spring in the M395HV I installed and I have great pressure throughout the range. If you install a Melling pump, the green (thicker) ring that comes with it is the correct one for our truck engines. Note, my engine is an aluminum block, so the high volume pumps are generally recommended for those applications because of greater thermal expansion of the block relative to the hardened steel parts operating within it.
Finally, the OP asked about the tensioner. We've seen the factory ones fail occasionally around here. Speaking for myself, I wouldn't even think of replacing the cam without replacing the tensioner. In my case, I was moving to a 3-bolt (non-VVT) cam, so I used the simpler LS1-style (bowtie) dampener and now won't need to worry about a tensioner failing in the future. It's a PITA to drop the pan to replace the pump, o-ring and tensioner, but the peace of mind that comes with it was worth it to me.