Here are things I have heard while waiting for the heads:
"You're better off just putting them back on, if you machine them without doing the block it will cause too much compression and you'll throw a rod"
"Shoulda just put liquid glass in it"
"You need a shim between the head and the block when you change the gasket or it will idle rough"
...anyone know about the last one? I haven't read anything about it in all my research.