Yes, pins can be made in any grade of steel you would like assuming that the material is available. Standard sized A325 bolts are a typical high strength alternative and are approximately 2.5 times stronger than standard pins which are typically made from low carbon steel wire. When using a high strength bolt as a pin you must take into consideration the thread length of the bolt to keep clear of the shear plane. A325’s are advantageous in this application since they have shorter thread length than standard bolts. Many times washers are included in the assembly as well as a locking nut since there is not a cotter pin to keep the clevis pin from coming loose.
Are high strength clevis pins available?
Can you adjust a clevis only tie rod assembly?
Yes, clevises do have a take up that rods can be screwed into to tighten the assembly. This is typically not as large an adjustment as a turnbuckle but can be several inches depending on the size of the clevis and the pin as you can see in the picture. You can also extend the assembly by about an inch but be careful to keep the entire neck of the clevis engaged with threads or risk the integrity of the assembly.