Since the material to change the stroke is coming off the bottom side of the crankshaft journal, the cam/rod relationship won't change much, if any. Also, I compare the dimensions of the rods I use against a stock stovebolt rod, and whittle on the rods if necessary. In most cases, the new rod has a slimmer contour than the original. I always static balance the rods to +/- 1/10 gram (a dollar bill weighs one gram) so any alteration of the rod contour gets compensated for during the balancing process.
