So, it was time to swap out the original full-figured flywheel for the new, dietetic one. Cover was off, so alternator off, and....
Big honking nut holding the flywheel on. Hmm. Need a 46mm socket. And a deep one at that. Poke around the stash. Have a shallow 46mm one from some gag a million years ago. Dig through catalogues. Only way to get a 46mm deep is 3/4" drive. Look for 1/2-3/4 adapter so I can use my impact gun. Can't find one.
Real socket is close to $50. Cheap Chinese stuff about $20.
Keep digging. Find a NOS Williams on Ebay and chisel him down to $15. Order the adapter.
When it all shows up I skim the face of the socket to get a better purchase on the nut. It's only about 10mm tall. The nut is in a recess, but the socket actually clears!
While digging, I find the 1/2-3/4 adapter I bought long ago and forgot about. Now I have two.
Put it all together and blast off the nut. Flywheel walks right off. Clean it all up a little Anti-Sieze on the splines, red Loctite on the threads, and it all jumps together.  
Modified Vulcan front pulley is on. Have to twiddle the alt cover for the later style starter gears. Then it can all go back together.