Well, last time out with my decently built pump gas 440, (mind you, first time out in a LONG time, lots of tuning yet to do) i went 7.60, (car has been 7.0s) the hellcat next to me went 6.46.
But, i do think that is a pretty good running cat, with an experienced cat driver. Most i see here, run between high sixes and low sevens.
My thoughts are....1. Build the biggest engine you can afford, within reason. I dont think i would recommend a 543, but i would suggest a 511. 2. Put the best heads on it you can afford. 3. You will need either a power adder, or cubic money, and cubic money still wont get you a comfortable pump gas street car that will outrun a hellcat. For a power adder, i would suggest nitrous. 6-71/8-71 blower kits arent exactly common, ive never seen in person a procharged 440 that i thought ran right, and though a turbo could make LOTS of power, there is lots of fabrication and tuning expertise required. Its not quite as easy as a turbo kit on an LS.
Good luck with your project, im sure you will get lots more opinions.