Help on rebuilding a 73 340

I have been running a 318 in my 70 Duster I just acquired a 73 340 which I understand is some what detuned from the earlier 340s I have a set of 302 heads but not sure if I should use those or the 340 heads that came on it and how about cams want to keep it a driver but would like to have a little more juice also should I stay with the stock intake manifold and Thermo quad or go with some after market. Would appreciate any advice you can give