318 with NOS?

So I'm trying to get more out of my 1970 318 for cheaper. I already have 340 J heads that have been ported and have 2.02 intake valves in them. A Holley 750 with vacuum secondary. The bottom end is all stock but is in good shape. I was thinking about putting in some nitrous but had some questions. First is it worth it? If so what kind of intake is going to give me the best results? Will I need to get a mechanical secondary carb? And how should the timing be set so I don't kill the engine?