Generaly speaking, most spindles have a flat edge on the fork section, clamp a section of alu angle to both spindles and that will square them up, then adj the ty-rod to that. Problem I have found with the "string method"(and have done it that way before) is that some builders dont used right and left rod ends when building the ty-rods and you have to remove it to adjust it and the whole car moves and you have to re-adjust the string. Square the spindles, adj the ty-rod, turn the ty-rod out 1 rotatetion (or each rod end once) attach steering rod and set steering wheel to desired possision ( may require rolling/towing)