1973 340, want more power.
Some folks just want a parts list... like in the hot rod magazines LOL. Not the way you or I would do it, but hey, different abilities and methods don't change the desire to reach the same end goal. I know I did my first engine 40+ year back from a lot of reading of the hot rod mags and the few books that were out there. I did not understand it all, nor do the optimum, but I sure was thrilled with the results and got a decently good combo (not a strip killer but a good all around performer on the street and highway).
Probably the one thing that helped was doing enough reading to at least compare and contrast and grasp the basics of what did what: cam sizes, breathing, compression, 'effective CR' (i.e. DCR), etc . Not everyone wants to do that..... that is just the way it is. When you are new to the game, lot's o' learning is a good step but even with some dedication, some basics is all most folks can handle in one throw; the curve to real knowledge is pretty steep and those who have it easily forget how far they have come.
Let's give credit to the OP for coming onboard and asking, and try to move things along. At least, he didn't just go out and order the whole Summit catalog LOL. I wonder if he is still listening... things DO get a bit off track from time to time.
Back to the most important questions: What is really wanted?
A true 12 second strip car (and is that 12.00 sec or 12.99 sec? It's a large difference....), or good highway cruiser with some decent punch? As pointed out, the best recommendations all flow from these answers.
Would it be fair to assume this is a stock 340?