I realize this is a very old thread, but just in case anyone is still interested, I happen to have my Cub engine on my workbench. Square barrel, '66 Mountain Cub motor - T20SM 653 16T. Weighs 58 pounds wet, with Amal Concentric mounted.
I just did exactly the same thing yesterday. Removed the engine, forks, subframe, everything. Down to just the main frame and swingarm. Took it over to my shop press and very easily pressed out the swingarm pivot spindle - no hammering necessary.
