Evil Dead Chainsaw

I have been working on an idea for an Evil Dead Chainsaw build.  However, I want to attempt to put in working sounds and movement of the chain.  I am not using this for a con, just a project that I want to attempt.  I would like to have a button that would provide a chainsaw idling sound when I turn it on.  Then, when i push another button I want to activate a servo to control the blade and making a high throttle sound at the same time. I original idea was to use a bike chain and sprocket for the blade that is powered by a continuous rotating servo.  However, I am a fairly decent worker with foam, but have never attempted to do anything with servos and sound.  I have also thought about purchasing the moving chainsaw from rubies or spirit and gutting the inner electronics and the blade however i was afraid of purchasing the chainsaw, and then breaking something on it and being out the $50.  How possible and/or difficult would this project be from an electrical point of a build?  Any help would be much appreciated.