People have been very thorough on this subject so i don't think there's very much i can add.
I learned that in in two identical displacement engines (in theory). The one with a larger stroke will get worse gas mileage because of the increased friction from the rod angle and will also wear out the rings faster because they're forced against the cylinder wall harder from the rod angle. BUT.......it will have better emissions becuase there's more tumble and atomization on the intake stroke because the air/fuel is pulled farther and the tendancy of the air/fuel is to "tumble" into the cylinder because of the angle of entry.
The advantage of a large bore, short stroke engine, is as stated that there's less friction and as a result can produce more power over the rpm range and because of port angle and cylinder fill rate, flow more air through the head at higher RPMs (port angle has advantages for both large stroke and large bore engines).
Another thing that i've read is that because of cylinder pressure and atomization of the air/fuel as well as the increased leverage of a longer stroke crankshaft, an engine with a larger stroke will produce it's peak torque and horsepower at a lower rpm than a large bore engine which has to generate more torque by increasing it's rpm operating range.
A stop-gap measure taken in the early 70's to come up with better emissions was to increase the stroke of existing engines and to engineer large stroke small bore engines. Some examples are the 400 Chevy engine, 400 Ford engine, (i think) the Chevy 305 engine, the Chrysler 400 engine (not sure on this one either) and a great example is the ford 255 made from '80 to '82 (or around those years). It had a decreased bore and the 3.00" stroke and was designed to be an emissions oriented engine. Remember that crap variable venturi carburetor, all of those were meant to lower emissions, but of course, didn't come into the public's favor.
-summary-
In terms of power, a short stroke engine will have a larger power band and can keep power in the rpm range better, but since it's operating range is higher in the power band it may lack some torque on the bottom end. A long stroke engine breathes really well at lower rpm and has increased leverage from the crank and better burn of the air/fuel mixture, but loses power on the top end faster because of friction.
If anyone disagrees, i'm open to any other ideas
