Aha...
http://www.wwiiaircraftperformance.org/f4f/fm-2.html
Same website. FM-2 performance information. It seems the FM-2 gets back what the F4F-4 lost. Seems like IL-2's performance numbers are pretty damn accurate for the FM-2. The F4F-4 might be a little on the fast side. F4F-3 seems about right too.