It should be relatively easy to duplicate saddle position w/r to BB and pedal axle, Also almost always easy to duplicate reach, though reach isn't necessarily distance from anything, rather it's the angle your upper arm makes with your torso when using the same bar grip. Thus stack has an influence on measured reach if you see what I mean. IOW if your arm angle remains constant, you can draw an arc with it's center being the top of the saddle and along this arc will be your combination of stack and reach.