Yes it will. Both blocks take the same bellhousings. Now, the 250 might not have the hole tapped for the correct starter for a 168 tooth flywheel, but you can either drill and tap it if necessary, or just use a 153 tooth flywheel and bellhousing.
Yes, as long as it has the Chevy bolt pattern.
Yes.
Yes it will with no problems.
Yes it will.
yes
The 2006 Lexus IS-250 has a 6-speed manual.
The 2010 Lexus IS-250 has a 6-speed manual.
The 2011 Lexus IS-250 has a 6-speed manual.
The 2012 Lexus IS-250 has a 6-speed manual.
The 2007 Lexus IS-250 has a 6-speed manual.
The 2009 Lexus IS-250 has a 6-speed manual.
The 2008 Lexus IS-250 has a 6-speed manual.