I remember hearing that 16x7 was that biggest you can go on a 1st gen, is this true? I found a cheap set of momo arrow 16x7.5 with 50 series rubber and unknown offset (but they came off a 89 240sx)

 

I run 16x7 (40mm offset)on my GSL-SE.

You have plenty of room to run more wheel in the rear, it's the front that gets you... you run into clearance issues on the inside anything more inboard than what I've got. If the entire extra half inch is on the outer edge you could get it to work with rolling the fenders a little..

Find out the offset & we'll see if they would work.