has anybody used these frame rails?

Installing a factory rail is much less complicated then just a square tube rail. Attaching all the upper control arm pieces to the rail will take a lot of measuring. If you don't have the equipment to do it correctly you will never get the front suspension aligned . How would you measure to install everything on a bare rail .

Find factory rails!
while I don't disagree with the amount of effort and precision it would take to mount the UCA/shock mounts and k-frame to the rails, street rodders do it with Mustang II pieces to stock frames or aftermarket/homemade. Could be done, just need to measure 5 or 6 times before welding. Maybe tack weld, mount suspension/steering components and take to a body shop to check alignment? then again, guys build "roundy-round" cars in their garages...maybe I'll hafta bug Ron, see if he's up for a project. Hmmm. Thanks for the input and thinking material.