z31 suspension parts will swap over. i found my self a wrecked 88' model (wide body) so i swapped out all mine with its rear subframe and it's FLCAs; big plus with the 88' was the HLSD. basically the same idea behind s14 on an s13; widening the track width. you can do the s13/14 FLCA, tie rods and front shock conversion, but i don't suggest it, the tie rods barely thread into the rack. if you look on f31club.org you'll find one guy that made his own front coilovers by modifying them to accept an insert and combined it with a ebay coilovers sleeves..looked great combined with 280zx rear coilovers.
drivetrain wise you can put just about anything in that bay, it's f**king massive. body wise, you're kind of SOL. i had been in contact with panda garage and they had found me a blown motor ultima but they wanted an arm, leg, and my first born to get all the body panels over here. i think the f31 chassis look soo good just as it is though.