If memory serves me correctly, the P-7 used the P-3 fuselage but went with a new wing and engines. I suspect you could approximate it by combining inverted C-130J nacelles and C-130J propellers with a P-3C kit.
For the Tyne-Orion, you'd need the Tynes from a suitable kit (in 1/72, a couple Breguet Atlantics or Transalls, in 1/144 the engines from a Vickers Vanguard) fitted to a P-3C.