If you want something really stout, the R230 diff from an Infinity Q45, or 300ZXTT will hold up to just about anything and comes with OEM VLSD.
Otherwise, most guys go with the R200 from the later 280Zs or ZXs. Those will take a good bit of punishment, but to be honest, if you will only have 250hp or so, in such a light car without slicks at the 1/4 mile (traction kills diffs, not hp), then just about any of them will be ok, including the smaller R180 from the earlier Zs. There is a picture side by side of the R180 and R230 on my website.
Hope this helps,
Tim