they may with some clever head work/manifolding
im with SK on this one, i cant see it being RB30 based, i rkn RB26 block with a mix-n-match storker kit, with at least one of the 3 components being custom, most lilely pistons or rods. cams would be big, my guess would be around the 256/64 mark, a little smaller than what SK said but with a smooth 900rpm idle, even with the ebst tuning getting cams like that to idle at 900 would be a stretch (i think so anyway, i have nowhere near the experience of SK)
i reckon all that low down power and torque is from manifolding and headwork, thats the 'secret' area.
so is this gonna be revealed at all anyway, or are we just stabbing in the dark for no reason? c'mon.... at least give us a hint? tell us whose closest to the real deal? please......