The textblock proportions are almost identical - about 2:1 [H:W] and the ratios of Page Height: Textblock Height are again almost spot on the same at 6:5 [Page H: Text Block H]. The page width of Intense Seeing is a bit wider but allowing for loss due to binding this will end up about the same.
Note that the absolute dimensions are quite different - the physical size of Opera Historica is 325 x 202 mm and the Intense Seeing page size is 248 x 171 mm (Pinched Crown Quarto).