Nice one Jon! I had a feeling that something like that had been tried. Any idea why it wasn't adopted? my guess would be that they were focussing more on the larger OV-10 Bronco by that point.
Fair enough (I'm just familiar with them from OH-58D and MQ-8C installations). I can think of several suitable candidates, but you'd need to extend the nose with some significant equipment to maintain weight and balance requirements of the aircraft. IMHO, I'd rather replace the existing engines with suitable turboprops and locate sensors either under the wings or in pylon-mounted pods (or, for a certain elegance, in forward extensions of the booms).
Probably the smart option as Jon's post demonstrates. I originally conceived the pusher-FAC as a clean-sheet-of-paper design (a faster, non-ducted fan Edgely Optica, basically) and it only occurred to me later that it could potentially be converted from an O-2. However, as the Basler/Spectrum/Sandcrab designs illustrate, a single rear engine is certainly feasible without too much compensating weight added forwards. If my helicopterish front end included an armoured floor, armoured seats, and possibly a flat sheet of toughened glass inside the rounded outer glazing* that would go a long way to balancing the rear engines.
*Yes I know that might cause problems with internal reflections, condensation and the like, but it's still worth exploring. Alternatively, it could be semi-Fw-189 style, with armoured flat panels on the lower nose and sides and a plastic canopy over the upper half.