Use fucking PMs, shit.
Go with aftermarket valve springs. ka24de.com sells a spring/retainer combo. $319 (set of 16 Titanium retainers and 16 Chrome-Silicon Spring pairs) which is what I highly recommend, seeing as the only way to make big power NA is to get rpms up and torque up.
-Jeff
__________________
** This space reserved for someone else's witty quote **