"changing rods to increase the cubes"
Rod length does not affect stroke or displacement.
The purpose of changing the rod is to use another rod journal diameter by grinding the crank undersize, but not concentric.
For example, if the rod journal were 2.25" now, reducing the diameter down to 2.0" which increases the stroke by the offset difference, a maximum of .25" in this case, then finding a suitable rod with that smaller journal size, length, width and pin size.
Alternatively, the rod journal size can be increased by welding but again not concentrically. You get the size increase as the stroke increase.
Whether this will fit in the engine or cause other problems is another matter, of course.
