340 Build
I agree with Strokerscamp about cutting on the heads.
I'm not as up to date on current parts as some other members that have done recent or are doing current builds so i won't provide any part numbers......
But, i would shoot for a comp. ratio in the mid to high nines, have a good competion valve job done, use a hydraulic Comp or Lunati cam with lift approching .500 and something like 235-240 duration at .050, a good set of headers (maybe TTI's), Eddy Rpm intake, a 750cfm carb of your choice ( i'm partial to Holley's) and some form of electronic ignition.
Once you have the specifics down on the engine and along with the 3.73 gear, you can contact a torque converter company and get a recommendation based on your combo. Something streetable that would flash stall up into the 3000-3500 range would be my guess.
Regardless of the horsepower number that should be a great sounding, fun ride for some street play.
This is just one opinion out of many possibilities. Good luck & have fun, Rick.
P.S. make sure you clean and put away all the factory parts you remove, they are like gold:D