how would you guys built it?

I just saw that a pair of EQ Magnums are only $650 or so, which is a great price for those heads. Add those, some KB107's like crackedback said, a Lunati Voodoo 268 or Comp XE268 cam, Edelbrock RPM or Air-Gap dual-plane, a 650-750 cfm carb (personally I'd recommend Carter or Eddy AVS), and a good 2.5" dual exhaust. If you don't have the cash you could probably get almost as good results with mildly ported and milled J heads and stock pistons.