I don't understand. The OP has spent a lot of money on a rear end that is sooooooo not optimal for the application, a crappy cam in a small cube motor, doesn't want to listen to reason and is now stating that he wants to spend MORE money on heads and useless roller rockers, and is looking for more performance. Makes absolutely NO sense. The heads are only as good as the rest of the combination. So, putting new heads on a crappy motor with a terrible O.D./rear end combo, added to a set of rockers is going to give you near ZERO performance upgrade and is nothing more than pissing more money out the window.
These are the questions that should have been asked BEFORE you spent money on a crap cam, wrong rear end and O.D. trans. The BEST preformance upgrade for the money is going to be a cam and lfter kit AND some rear end gears. Period. If you want a bit more then get some heads. If you don't like the answers you get you shouldn't ask the questions. It's really that simple.