i have an s13 rear subframe in my 72 510......but i used the motorsport auto (MSA) coil overs on my 280z...
it can be done. just befriend a fab guy
here's my 510 build,
240Atlanta.com
as far as parts for your s30, check out Dave @
Arizona Z Car he makes some bad ass stuff
and/or
Z Car Parts.com -- Motorsport Auto -- Home is MSA.
i have the msa type3 aero on my 71 240z getting boosted LS1 ^^
hybridz.org is good for you too
Dave