Mike, So sorry to hear of your tragic loss, Sounds like your life was made so much better just for having your wife in it.
(I fully understand you not wanting any more jokes, my wife and her health is one of the few things I won't joke about)
Anyway back to the original query, Its been a long time since I kept any fish, But when I last had them and moved them I did pretty much what you are planning, I had a holder tank which I filled with gravel and water from the existing tank (Was about 25% volume of new tank) the fish were happy in there for the day it took to get everything sorted out. I then washed all the gravel from the old tank, put into the new one, filled to about 60% full and then added water/fish from the holder tank. I then carefully and gently topped up the tank. I'll be honest the fish were a bit unappy for a day or two at most but no major traumas. Hope that helps.