What required the cutting off of the baseplate, I have had some pretty nasty ones but hanve always got them off without damaging the crank.
1st way I do it: feed in a heap of fairly thick cotton rope through the spark plug hole to lock the rotating assembly, put correct size socket on the nut (1" or slightly bigger, cant remember I just pull the right one out of my set), slide a 5ft breaker bar over my ratchet handle and undo it.
If that fails (rarely) I cut a small amount of the nut (as close to the crankshaft as possible but not actually on the crank) on opposite sides and break the nut in half with a cold chisel.
The good ole full cranks are a dying breed, it will be good to see this one rebuilt.
