I believe if you get any aftermarket cam gears set(i.e. tomei,toda, hks) no matter what it will get ride of the VVI. You could even just use a S13 cam gear to get ride of the VVI, but you'll loose your low end. For cam shafts I would recommend the 256 degree cams, your not going to get a lot of lop with these, to accomplish this you would have to step up to the 260ish and above area to generate a loop like a V8. If you go with cam shafts that big you'll need to upgrade : valve springs,retainers,rocker arm stoppers, pretty much the whole head. I currently have a S14 blacktop also outta a 1998 silvia. I'm currently building mine so i'll probably go with the tomei pro cams and pro cam shafts, they are one of the easiest ones to install.
pon cam is 256 is 11.5inches of liftpro cam is 260 is 12.0 inches of liftpro cam is 270 is 12.5 inches of lift
give the guys at phase2motortrend a call they will point you in the right direction.
http://www.phase2motortrend.com
For you i'd stay with the 256 combo, you can still retain your stock cam gears and keep the vvi, the only down side is that you wont get a decent size lop.
let me know if you have any other questions.