Bayrunner:
All the above posts hit the mark about the [domestic] 250 rod being usable in the 200 block. The 200 and 250 rods share the same big end dimension of 2.1236" and I presume (but don't know for a fact) that the small ends match as well. So the questions is whether, with a custom piston package, you could use the 250 [long] rod in the 200 block to improve the rod ratio and reduce the cylinder side loading. Unfortunately, there just doesn't seem to be enough room to make this work.
If you are assuming a zero deck, then you can compute the required custom piston pin height as follows:
Pin.height = 200.block.height - (200.crank.stroke / 2) - 250.rod.cc.length
Pin.height = 7.808" - (3.126" / 2) - 5.880"
0.365" = 7.808" - 1.563" - 5.880"
If I've done the math properly, the custom piston package would require a pin height of just over 1/3 of an inch (at 0.365") and that just isn't doable. The shortest pin height I've seen used was somewhere in the 1.120" range and that's short enough that the pin hole intersects with the 3rd (oil) ring land, requiring a "support".
Russ