Always possible to convert to electric PTO.
Not sure with Honda's of that era if they all had the same rectifier output or not.
All you will need to do is find an electric clutch, cut the PTO pulley off your engine stack and fit some sort of stop to prevent the clutch spinning.
And of course a switch, a simple toggle will be fine.
On the deck simply put a spring where the tensioning rod / wire went to keep a constant tension on the belt.
If the alternator can not keep up with the clutch's demand, you might need to pop the mower on a trickle charger between uses.
