The stroke of the 292 is actually 4.120", not 4.125" and the bore is 3.875" not 3.75". Small difference but it can skew results. Also, you will find that software doesn't accurately predict results from changes done to siamese port engines. So this may be an exercise in futility and frustration. However, there has been a lot of dyno testing done to these engines that can show very closely what can be achieved with various components.
