I would recomend that you change oil and put in AeroShell Fluid 2F, it is designed to prevent corrosion while the engine is inactive for months. http://www.shell.com/business-customers/aviation/aeroshell/aeroshell-hydraulic-fluid/fluids-and-preservatives-2f.html
If you have it stored in a humid area of the country I would consider this mandatory, as Lycomings are prone to cam and lifter rust when not flown regularly.
I would also remove the top spark plugs and install descant plugs, and securely tape the exhaust pipe closed.
The Lycoming Service Letter is: SL 180B.
Bill becker