383 for a 67 cuda

I can agree with stock heads being a big cork. Really starving the engine of fuel and air. I was looking a few sets on jegs and summit racing. The only problem I am concerned with is buying a set of heads that are to big or too small. Are there any guideline too figure out what heads you will need as well as cams to maximize performance from different engine setups?
I'm not worried about you looking for answers. Thats why we are here asking the questions. and it looks like we are both working the same engine just to different levels.