I hated my Spitfire engine, but you could easily fit two of them in that space.
Height is the killer (as learned from trying to find an engine to fit in the space of a Spitfire engine). If you can add a few inches to the height, the length and width are very easily attainable from a plethora of modern engines.
If you can fudge on the height, look at a Miata drivetrain.
Lemons South 2008 - Fail, Lemons South Spring 2009 - Fail, Lemons Detroit(ish) 2008 - Fail, Lemons South Fall 2009 - Fail, Lamest Day 2009 - Fail, Miami 2010 (Chump) - 2nd!, Sebring 2010 (Chump) - Fail, Cuba 2010 - Crew Chief, Roebling 2011 (Chump) - 8th!, Sebring 2011(Chump) - 19th!