I figured I would share my info in case anyone found it usefull:

I have 280ZX struts that have been cut down so that the internal depth is 13.5 inches. I used W20 MR2 front struts inserts which are 13.25 so I needed to space them up. I used a 6mm thick washer, I had several extra crank bolt/pully washers and as it was a good fit in it went. The only issues A. were the weld where the halves are put together protruded far enough inside the tube that I had to use my longest rat tall fill and smooth it down until the strut insert fit inside and B. the the damper rod being 1 mm smaller than standard diameter meant I had to come up with a shim/collar to take up the slack inside the spherical bearing on the camber plate.
The plus side is there are plenty of options for the MR2