Yes...6 psi on E70 with LT4 fueling shouldn't be a problem.
Jenetty racing did a Whipple setup On E60 with 3.25 pulley and LT4 fuel system. It made 620whp @ 9psi. Everything else was stock down to the airbox. It did not have enough fuel system to do any more mods like a larger throttle body, big gulp intake, Cat deletes or Headers which would likely add another 60-80whp.
https://www.camaro6.com/forums/showthread.php?t=502348
E55-E60 is really the sweet spot anyway. We can get pretty much all of the timing on E60. Mine only drops 1 degree from full pump E to E55-60.
Even a bolt-on LT1 car gained 20whp on E46, so it might of made another 5-6whp @ E78. Look up RPM's youtube channel they just tested it.