My thoughts on increasing the stroke with the same bore makes me think that the longer stroke will suck more air and fuel into the cylinders with the everything else remaining the same RPM are RPM, the motors knows how much air and fuel are run through it, I don't think it knows about piston speed or rod angles, does it
My thinking on piston speed and ring drag is the piston travels the same RPM but not as far on the short stroke motors, the motor doesn't know the feet or inches traveled per second
Hence more power with the longer stroke (within reason)
IHTHs