Sigh... no one can tell you what is a waste of money and what is not.
If you are going to cam a stock head combo you have to decide how much power you are willing to give up to maintain near stock drive-ability, or conversely, how much drive-ability you are willing to give up in the name of power... or how much of both you are willing to give up to keep most of each.
Once you determine your goals my advice on ensuring your goals are met would be to contact a cam designer. My money goes to Buddy Rawls (3 times now) as he seems to really enjoying making something out of what most refer to as "nothing".
A custom cam, spring package... you'll be looking at the better part of $500 to make about 25-30rwhp more then what you are looking at now.(or more hp if you want to sacrifice more drive-ability).
Or go with the F-cam and spring package for the better part of $400 to make about 15-20rwhp more and give up some drive-ability to the custom at the same time.
What the guys above are not making clear is, with aftermarket heads you can make the same power, or more without giving up drive-ability.
But to say cam'n E7's is a waste of money... well... once you have done all the bolt ons to a stock long block, you will be hard pressed to make 30+ wheel hp for $500.
Sure you can pick up GT40's cheap, but once they are cleaned and freshened up you've not saved any money over the custom cam route.