why bother cutting and shutting for a pissy 10mm. just take the track improvement and use it properly. Dont know how you think s13 castor rods will fit a ae71/ae86/ke70 mount unless you plan on remaking the body mount??

you can use a ae86 front end with a s13 rear end, or simply redrill one hole in the s13 lca and bolt it together.

there is also a thread with a bazillion pages that covers most/all of this anyways...