Thank you all!

[pdb]

I went from having a busted float bowl and a seized piston/crankshaft on my 40 Featherweight to having a fully functioning engine in one afternoon (not counting a few days needed to allow penetrating oil to work.)

After removing the carb, soaking the piston in penetrating oil, a judicious application of heat, a fair bit of pounding with an oak dowel on the piston surface through the spark plug hole and some taps with a wrench on the flywheel nut, I got the piston free. I worked it by hand for a while and it appeared to be moving freely again nicely. The gear box and prop were turning nicely so and I could see a spark so, what the hell...fill the gear box with the elusive SAE 140 wgt, fill the trash can with dihydrogen monoxide borrowed from Scotty of the Enterprise, and time to give it a try starting.

Unbelieveable! Five pulls in the cord and it starts right up, purring away, good cooling flow from the base of the engine block, and smooth running. I am beginning to feel like a real mechanic. I thought I had a major rebuild on my (less than capable) hands, or more likely, a boat anchor.

I really appreciate the help from this crew. Thank you all for the helpful suggestions and inspiration.