If you are adding new live rock you might as well treat it like a new tank setup. Feel free to use some of the existing water from your existing tank but there isn't a lot of bacteria in the water column. If its cured rock then there won't be much of a cycle, if it isn't you will have to wait a few weeks to a month for it to cycle.
I would take a few pieces of your current live rock and put it in the new tank just to help seed the new live rock and sand. Taking the live rock out of the water is fine as long as its only a short period of time (upstairs to downstairs is good, out of water for hours is bad)
Also most importantly what kind of live stock do you have? It is strongly recommended that you drip acclimate them into the new tank after they come out of the 65. Try and match the two tanks in salinity and tempurature to make the process that much more seamless. Oh and good luck!
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