Hi John,
You're now into a somewhat more tricky job now, if you have been unbale to pull the adapter boss off so far, the chances are its rusted on are very high.
I did mention in an earlier reply that you may well come up against this problem due to the nature of your initial problem with the pto shaft .
The adapter boss is a sliding fit onto the crankshaft and secured with bolts to the crankshaft pulley wheel, the splines are a very snug fit to be honest, and with all that salt air/water in your location its going to a right pain to shift.
Your options for an effective removal of the boss are limited now due to the proximity to the timing cover/ crank seals etc and also the very high possibility of causing damange to the end of the crankshaft.
Using excessive heat is not ideal, nor is geting brutal with a hammer.
You may want to try the "hole & fluid " method again, but i think given all considerations i would carefully cut it off.
As per before, i'd run a parallel cuts along two or three sides, then use a smaller dremmel or similar to do the cuts on the boss face, then gently pry the cuts open a small amount, cover the boss with P fluid and leave for a short while.
have a cup of tea then go back and gently leaver or pry it off, it should come of without to much force.
This method may hopefully keep the crank and other ass parts in the best possible condition and avoid a more costly repair bill..
hope this helps a bit.
rob