if you're going to use those heads i'd have them cut down as close to 70 cc's as possible or just get on ebay or some of those used parts for sale sites,and there are many so take your time and find a better set of heads.you didn't say what size the valves are in yours but you most likely need to lower your compression.
everyone seems to think the vortec heads are the hot ticket these days because of price but i'll have to say i think in the long run you can do better.i bought a set of iron bowties 2 yrs. ago and had 2.05 valves put in before they were sent to me for less than $850.00 and i am very happy with them and the'll last forever having alot of extra material in the for porting.
so if you do some work to your heads or get new ones and start with a good electical system like MSD,carburation,intake asyou mentioned,headers and exaust and finally cam you should be set to hit the 12-13 sec. range.the rpm or torker cam should be good for a light car like yours.
you want about 180 lbs. of cylinder pres. if you can get it.i've used 350 head gaskets as opposed to a shim on my 406 in the past to help with this.good luck.
p.s. remember to use quality parts beause the time spent down and the money spent twice is just harder and more expensive.also you're going to need a tork converter.about 2800 stall.tci,coan,j.w. perf.trans,b&m,hughes,buaman,art carr,
its important not to go cheap here.go online with a converter company and describe your set-up and give them your cam srecs. and they will get you the right converter.i exspect it will be around 2800.