degeko - I can't see the RB20 having these issues so go for it.
dave - my oil pump was the same in the sense that it had room for the longer driver on the crank but the crank was a short drive. Perhaps all the oil pumps are like this and the RB26 cranks with the longer drive are just modified due to the discovery of this issue.
I can't see that they found this out on the street. Somebody must have been racing the R32 GTR's and found this to be a problem, communicated it back to Nissan who made the change just in case.