I stay away from aluminum blocks but the guy I work with does a few every year. I know he pays a lot of attention to main bearing clearances and he pins the cam bearings. He also usually puts the block in an oven so he can verify that the sleeves have properly dropped into position. And then there is some sort of trick on surfacing the blocks to make sure the head gaskets seal on both the steel sleeves as well as the water passages. Lots of little details to watch out for and every block mfg does different things so you have to really pay attention between Indy, Dart, Brodix, etc. They all have their own little quirks. For example, some aluminum blocks require special head studs.