If your talking about purely the 'cylinder block' i don't think you can. Pretty sure the 16v has oil jets or such like and the 8v don't. Don't quote me on this as i cant find any info on it.
the basic block is pretty much the same, as well as the cooling jets it also has a breather on the front. you'll need to change the pistons, intermediate shaft, oil pump and both timing belt sprockets