When I got to that point in the Project Remote Control build, I did a quick mockup with the customer, noted the clearance issues as we were tilting the bib up into place, and made adjustments accordingly. The thought of redrilling the anchor bolts never crossed either of our minds. I can’t remember for sure, (long enough ago that my mother was still alive) but I think I ovaled the frame mounting tabs back somewhere between a 1/4&3/8” to set the core support back in, check fan clearances, retest the bib clearance etc.
He had bought a shiny new replacement clutch drive fan blade for an FJ60 with the extra mini fins on the front face. They became a problem in the tighter space, and we reverted to his original 78 fan, which was still solid, just yellowed. The final decision was to leave the core support at its new position, and take slightly more off the two strut rods, tilting the whole assembly in for just the last bit of room. I don’t remember all the measurements that went into making that call, but I am sure that is what we did, and it was the best solution for his truck.
Hth