Yep its a bit big, but the one in the bottom of the rad has been ditched due to me fitting a manual radiator (koyo) so this will be doing the job all on its own. Hopefully its not too big it cools the fluid too much and wont drop into overdrive as a result. By the way this is the biggest you'll get away with on a JZA.. its 13"x10" fin size (pipes stick out another 2" either side) and only just fits.
I've used the hoses and clamps that came with the cooler, i dont think theres much chance of hoses popping off as they were *really* tight to fit on in the first place.. so they should be okay, although one hose i had to replace with one from a hydraulic suppliers.. rated at 400psi.. enough you think? The cooler booklet only states 150psi hoses.