You're on the same boat as me. I have a s14 4-lug and got H&R spacers. Got the s13 application and it didn't fit. But wherever you order, specify what you need. Every spacers ordered to H&R are actually custom, it's just that they advertise packages which are most popular (I was told that by H&R marketing dept). What you need is:
FRONT: 12x1.25 (Threading),
14.25mm (shoulder=The part that fits on the hub),
42mm + spacer size (Length of bolts).
REAR: Same as S13.
That's what I did (Actually did a special order at H&R for the front lugs
).
Hope that takes care of business.