For the vets out there what do you think the max limit is to lengthen Femur to look absolutely normal nked? What about tibia?

By absolutely normal I mean not to trade height phobia for proportion phobia afterwards. Looking at femur/tibia ratio and looking or feeling bad. Most importantly not needing to HIDE it! I have read some diaries that have done very moderate 5-6cm on femurs and they have said that they look better proportionately. So opinions please...