well....
I am currently using completely custom machined rods and pistons. The rods are an H-beam style 6.000 inches long with a journal of 2.100 and a pin dia of .928. (yes offset stroke to SBC) The rod bearings are completely hand made to fit the crank and the custom rods. The pistons are custom Ross Racing Pistons made for an overbore of .050. Yielding a total of 4.13 liters.
Not to try and disagree with you on the stroke theroy of offset grinding but I have done this several times. So, if you were to offset grind a stock SC crank with rod journal Dia of 2.311 to a small journal SBC journal of 2.000 it would yield .300 of extra stroke. It gives you an additional .150 of stroke at BDC and an additional stroke of .150 at TDC.
I even went to far as to draw a simple picture to full scale so it would make sense to everyone. It took me a long time to understand when I first started stroking car engines so I thought it would help.
The difference in journal sizes is aprox .300. Yet the centerline of each rod journal only moves .150. But you get this additional .150 of stroke at the TDC position and the BDC position yielding and overall gain of .300.
Same would happen if you were to use the stock SBC journal of 2.100. You would gain and additional .100 at BDC and TDC yielding and additional .200 of extra stroke.
If the picture doesn't make sense get a plain piece of paper as I did and draw a straight line on it. Take a compass and draw a 3.39 circle in the middle for the stock SC stroke. (1.695 radius) Then where the circle you have just drawn meets the straight line draw (2) 2.311 stock SC journals. This gives you the TDC positions and the BDC positions. Next draw two 2.000 journals starting with the outer edge of the stock SC journal as I have done. Then you can physically measure them to check. It doens't have to be perfect to get the idea.
I hope this clears up anyones questions to what I have in my engine as far as rods and pistons and how an offset grinding works. There are other issues such as rod clearances with the side of the block and counter weight issues and the piston when it is at BDC but they can be worked out.
Chris