First, smoking for 618 hours did seem just a little long. I know some guys like a LOT of smoke, but dang!
Secondly, 120 degrees will NOT deal with the bacteria such as salmonella or e. coli. In fact, holding at 120 degrees creates an environment where it will flourish and multiply. The minimum temp is 140, and you should hold it at that temp for at least an hour in order to get a good kill on those heartless little s.o.b.s. You do not want to get much above 140 or you run the risk of rendering all your fat and having it all drain down to one end of the sausage (don't ask me how I know that your salami will be dried out and wrinkly on one end with the other end being fat and greasy on the other.) And I cannot strongly recommend enough that you use beef fat (and the kidney fat if at all possible) rather than pork fat. Beef fat has a higher melting point and is more flavorless. It also doesn't give you as greasy a mouth-feel as the pork. The kidney fat is the whitest in color and the firmest fats because it has the highest temp melting point of all. It is the superior grade and you will be a lucky so-and-so if you can find a source. For that matter, rendered out it makes the BEST fat for deep frying EVER! Best french fries in the world, hands down.
And definitely do the cold water rinse, or even plunge them into a tub of icewater! You want that cooking to stop instead of letting it "rest" like you would a turkey or a roast. The resting period often sees the temps creep up a few degrees internally and that can further render out the fat in the sausage. You want to be able to see the little bits of fat in between the bits of meat, rather than having it melt and turn the whole stick to a sodden greasy mess. And like Stoker says, you do not want it sitting at the warm temp for long. Warm means happy, happy bacteria breeding like crazy and planning on turning your guts into a raging firehose.
Oh, and the recipe says to have the meat at 38 degrees before grinding? A trick I picked up in the last few years is to get those temps even lower and if the meat is cubed and partially frozen, so much the better! It actually grinds easier and produces a better texture than if it is too warm. Nowdays I even put the grinder components in the freezer the night before in order to keep everything at a lower temp. As meat goes through the grinder, the friction of the works warms it up, so colder start-up prevents warming the meat too much, too.
Another tip! Do not wait until the meat is ground to add and mix spices. I have been adding the salts and spices (and even wine) as soon as it is cubed and going into the fridge to rest and cure. In the wee morning hours, I transfer it to baking sheets in the freezer to get it partially frozen just prior to grinding. If it is well distributed through the meat, the grinding mixes it in further saving you from using your bare hands turning it over and over (my hands cannot take the cold anymore and even with a 5 minute hot water and antibacterial soap surgical suite scrub like they do in a hospital, your hands still carry a heck of a lot of bacteria. Heck, surgeons still put on gloves AFTER the requisite 5 minute scalding hot scrub!) One mix for when it grinds, and it mixes again when you run it through the stuffer. Mixed is mixed, let the machine do the work!
MAN, I LOVE MAKING SAUSAGE! I have been waiting for pork to go on sale so I can make breakfast sausage for Black Hills Turkey Camp this spring. I imagine whoever is coming is bringing an appetite, right?
Good luck stuffing!