How do you make 350+hp in a 350??

[chevyc1068]

I'm looking at pulling a 350 out of a 69 c10 that supposedly has about 60-70k miles on it since a rebuild and I'm not for sure how many before that. I don't know because the previous owner put in this engine after the old one wore out, and this one was just a rebuilt one. Though it is still supposed to be a 69 350. Ok, enough with the life history. I want to make this engine produce 350+hp and if possible 400+ torque. So what parts do I need to put on this to do that. I'm looking at rebuilding the stock heads, new cam, intake, carb, headers with dual exhaust, all that good stuff. I will also be rebuilding it, pistons, rings, gaskets, timing etc. But no nitrous or blower systems. I would like to keep the fuel economy fairly high since this will be a daily driver, though I want some power to set me back in my seat when a really romp on it. I need good low end torque but would also like to be cruisin at 60mph and romp on it to pass someone and be able to tear right past them. So first of all do you think I can achieve that much power with an old motor or will I find all the weak spots. So if you made it this far without giving up, any suggestions???

I could really use your input on this.