there were actually a lot of s30's made, there were over 363,000 sold in the US alone! suspension setup depends on what you want to do, ST springs and Tokiko's are a nice streetable setup, MSA swaybars are a nice combo
http://www.zcarparts.com full coil overs and sectioned struts is the only way to go, here si a writeup I didhttp://forums.nicoclub.com/zerothread?id=237090
as for tracking the brakes are a real weak point, again, lots of options, toyota 4 pot calipers on vented z31 disks and maxima read disks are popular and cheap upgrades, or you can go for wilwoods, form arizonazcar, or modern motorsports
as fro engine swaps, I'm a fan of the L28, especially after spending some time and money on my Z32, info on every swap possible can be found at hybridz.org
please keep us informed of what you get and what you do to it, and feel free to post questions, I have done abotu everything possible to my 240Z