I also have a home made flywheel puller of the same type, Joe Brown made it for me. they are awesome.
To remove the scum and garbage from alloy engine casings I strip them bare and soak them in paint thinner. THIS WILL DESTROY RUBBER SEALS. once soaked I scrub them with a wire brush, and from there polish them up with green scourers and leave to dry. To remove paint I use paint stripper as well..
