If you dump the clutch at an idle... you will stall the engine..right? You have to get the RPMs into the power band so that doesn't happen. You have two different engines that have different "power band" ranges. The torque curve will be flatter on the 292, and the 283 will most likely be less flat (torque range is shorter or at a higher RPM) meaning that you could dump the clutch on the 292 at a lower RPM than you could on the 283 without stalling the engine. The 292 power band starts at a lower RPM.
Stroke and displacement will "both" change the characteristics of any engine. If you install the 283, the rpms at any given operating speed will be the same. If you are not in the power band, it will take more work for the engine to get into that power band. You would have to change the ratios in the tranny or rear end to compensate.
Instead of me trying to explain more, maybe this article will shed some light better?
http://www.vettenet.org/torquehp.html
