I'm rebuilding my 4.0 Cherokee. I want to use the longer stroke crank from the earlier Jeep/AMC. I'd like to get a 3.9" stroke crank.There are several displacements for the straight six. I don't know if the differences are due to stroke or bore or both. Could you list the bore-stroke numbers for the different engines? 232, 242, 252, etc. What years had which engine? Thanks.