I couldn't find any info about the fitment of 300zx tt wheels on a 240sx.  I wasn't sure if spacers were necessary in order for the wider tires to fit. 

I can tell you with confidence that the 300zx wheels fit without any additional hardware.  They fill up the wheel wells and give the 240 a much more aggressive stance.

I also mounted the "rear" wheels in the front and they clear everything properly.