body alignment help wanted

[cypress TX 72]

I have my cab on but not bolted down yet, and I have my core support on, but not tightened yet. I have the inner wheel wells bolted to the quarters and on the truck, but it is not lined up correctly.
the fan shroud is the give away - the fan is rubbing on the shroud on the drivers side and there is a gap on the passenger side.
Now I know this sounds like a simple solution, but I have measured out the cab from the frame rails and it is with in a quarter inch. It feels like I have the core support moved all the way over as far as it can go and that helped a little - but still not enough for the front grill to go around the lights.

Can any of you experienced rodders give me any learned tricks or any advise on making this right? Is there some measurement points that I can go by that may help me?

Thanks for any help I can get.
T