I'm going to agree with about half of the answers. I think you will run out of suspension tavel unless swapping over to Z-car struts. 280ZX fronts, I believe are the tric setup for a PL-510 (1600) so they would probably work for you too. Tensandtwenties may be able to answer this one better. John?
As for the safety issue of cut springs, that is where I'm going to disagree. I have run cut springs in almost all of my Datsuns and have NEVER had a problem. I have used everything from zip ties to stainless steel safety wire (and once or twice nothing but gravity and pig ignorance) to hold the springs in place. If it does worry you, after you cut the spring to half a coil higher than your final ride height, heat the coil and bend it flat instead of cutting the last time. That will approximate the "locating coil" of the stock setup. Again, I have never done that and have had no problems.