Agreed, 280whp will run 12's, with a killer, 1.95 or better 60' - probably not going to happen in a GTP unless you've got drag radials or slicks. 330whp will run 12's even on a soft launch because it'll back half a lot quicker.
Maybe I'm off the mark, but won't a 3.25" on a ported blower with rockers/headers/good tune/plugs/stat/intake make aprx 280whp safely w/o an intercooler on pump gas? Maybe closer to 270whp, and then adding an intercooler and more boost would make 300whp?