What to look for when buying a block?

[N777CK T]

Hi, I want to look at a couple of blocks for sale for my 13b FD3S twin turbo.

What would you look for when buying a block? I understand with a piston engine there are things you can do to check if it turns ok, piston slap, crank movement etc
Is rust on a block an issue? How would you tell if it has had new parts \\ been rebuilt etc?

Hopfeully someone knowlegdable can help out!

[ashc]

apart from general condition, stripped studs etc,  i suppose 3 decent regular whoosh sounds when turning the main pulley might be helpful? Can also see state of the central part of the apex seals through the exhaust ports too.

[N777CK T]

Ok thanks, I can\'t say I know what a decent whoosh sound is like but I\'m guessing a slightly punchy\\pressured sound?
Would this be a quieter sound than a piston engine because of the fact the 3 divisions of the \'chamber\' are smaller? Or is it the opposite?

And I\'m guessing the apex seals/tips should just look fairly squared and thick to be in good order?