Hello,
I am not a tie rod specialist, so I do not know the specific load pattern for such piece of equipment (you are talking about a tie rod in a car steering system right?), but it appears to me that a tie rod, although they might come in a lot a shape, can be viewed as a cylindrical beam used to transmit a compressive or tensile force ( along its axis). So, if you intend to cut that cylinder and fully weld it back together with a homogeneous material, you have the same area to transmit the forces, therefor the same static stress. It should withstand the same load for the same lifetime. Hence, you don't have to prove that the clevis and the rod end are critical.
Being shorter, it will be less prone to buckling. If the welding is done properly (no cracks), there should not be a problem with fatigue.
hope I understand your problem correctly and I could help. If not, can you give us a little bit more information on the tie rod geometry and the loading pattern.