building a 383 Stroker with Factory parts help needed

Yes that is correct. A 440 crank and 440 rods will make a low deck 426 in a standard bore 383 block. The hard part is finding a machine shop who is willing to that work. You might find that it is cheaper and easier to just sell the 440 crank and then buy a new stroker crank. I used to build stroker motors using factory parts but that was 20 years ago. I wouldn't bother doing it these days but I won't stop you if that is what turns your crank.