I also have a Super 55 that I plan on rebuilding an engine in this winter and possibly adding the bigger 550 sleeves and pistons.  Is this a good swap to make?  Will it work?  Is there anything else I should know about making this work?  Do I need to switch to a different intake manifold or carburetor?  My tractor was built in 1955 and has a Marvel Schebler carburetor.  I look forward to hearing your responses.  Thanks!  What a great forum!