As noted the 3L has same stroke/rods etc but different bore (actually slightly siamezed).
As far as max RPM been trying to get a concensus on max safe RPM on stock block/valvetrain. Can say that Chris Reinke's 260+ HP Duratec Touring car used stock rods and valvetrain (except 3L valves) with an 8000 RPM redline with no problems. Course, he may have rebuilt the engine frequently?? Mirko once said 7800 RPMs safe IIRC. But would longevity suffer?? The crank whip/harmonics issue may well be worstened at high RPM. The dual mode damper would be a wise & cheap precaution for increased redlines. So would an Accusump. With these 2 precautions, I "think" that a 7500 RPM that is visited briefly (as opposed to sustained) may be reasonable, though normal longevity may still suffer somewhat. Just do not think anyone knows for sure..
