I was working on a 60 cm model but stopped to take a break from it. Can you share a link to the model that you have found!
in the download section here all the capital class ship models by Millenniumfalsehood are the same scale and he has several star destroyers. both the imperial SD 1 and 2 are 24 inches long when printed on standard letter size cardstock. I have built 1 of each class SDs. the ISD 1&2 the Victory class 1&2 and the Venator class. They are fairly easy to build, and easy to add detail to. it took me a month to a month and a half to build each, because I added a lot of internal structure, and a lot of external detail.