are the 1.6 rockers you have self-aligning? If not you'll have to put guideplates on the Vortecs. The heads are going to need some basic machine work... The springs have to be replaced (I run 1.32" LT4 valve springs - they're REAL cheap and work great get them at
www.sdpc2000.com), get screw-in rocker studs installed, and depending on what cam you go with you might need to get the guide bosses cut down to accept more lift. Typically Vortecs run into guide-to-retainer issues around .470" lift but not all are cast equally (mine had over .560" of clearance). All this machine work is really basic any half-competent machine shop can do it and it shouldnt cost more than $200 for everything.
I'd probably go with an RPM vortec intake, Comp's XE268 cam, 750 Holley VS, and a rebuilt junkyard HEI. For exhaust 1 5/8" headers with a typical 3" cat-back of your choice... I'm assuming the cars auto so while i was at it I'd replace the convertor with something a bit looser - if its a 700R4 maybe look for a convertor out of a 4.3L S10. Get some 3.42-3.73 gears too.. A combo like that shouldnt have too much trouble hitting atleast low 13's possibly high 12's with optimal gears and stall