Saving Old Seagulls

Sorry for this posting as I'm sure it's been addressed several times. Searched but found little aside from giving it a good beating. I have followed the whacking procedures with no success. Penetrating fluid applied for days. Really don't want to hit it any harder for fear of damage. Any thoughts on heating the flywheel to loosen it?
Thanks for any thoughts
It's a 74 Forty Plus.

Have not needed to use heat on any of mine, here is my setup, this was removing the flywheel on the Century Plus. First a ball bearing to transfer the blow to the shaft. Then hang the engine from a beam clear of everything.
As you can see the climbing cermantle rope is quite long so I can get a good clear swing with the hammer. It’s important to set the height up so you can stand well and strike from the shoulder. The hammer needs to be moving quickly and strike the nut squarely so the length of the head is in line with the shaft.
This is the hammer I used it’s a good sized ball pein and is much better than a lump hammer, the ideal hammer would be a maul because of the length of the head, but that was down the boat shed.

Strike quick and accurately.

Dave.