I have a couple of 3S NA blocks from a late MR2 where they have the strengthened corner by the water pump just like the late 5S blocks.
Internet rumour also says that the metal composition is stronger blah blah.
These blocks are easy to use on turbos, simply tap for a turbo oil feed.
Common to do now and hard to get hold of.
Standard 86mm bore in good condition.£300 posted / £250 collected each. Based in West Sussex.