That is the reason I am looking for a crank. I bought a complete bottom end off ebay that was suppose to be good. Everything looked and felt good so I went ahead and put it together. When I started it it had a little noise and it got louder. When I took it apart I found that the front rod bearing had spun and the bottom bearing was under the top bearing.
I have found some 650 cranks. If I am correct the 650 crank has a shorter stroke and longer rods. So the piston pin height is the same on the 650 piston and the 700 pistons. So you should be able to use 650 crank and rods and 700 pistons and cyl. together and get the same piston to deck height and the same compression. Has anyone done this?