Auto body repair & detailing: Roof replacement, spot welds, body professionals

Question
 I have a 1956 Ford truck with rust all around the drip rails.The previous owner filled in the drip rails with fiberglass and painted  it. I did not notice it untel it was to late.The best way to fix it is to replace the roof. I have a spare cab with a good roof. My question is this- how hard is it to replace the top part of the roof. Is there a good spot to cut? Is there any special bracing I should use to hold the A and B pillars in place? Any advice will be greatly appreciated.

Answer
Cut off the old roof SKIN ONLY- see if the supporting structure is in good shape. If the supporting structure is intact, then spot weld drill off the donor roof skin and glue/weld it to the existing truck. Cutting the entire roof off at the a and b pillars is the realm of true body professionals- it's a real bear to get the doors and glass to fit properly. If there are lead seams, which I have no idea on a truck as old as yours has them, I would cut the skin above or below the lead seam and graft it together (with an overlap of at least 1 inch) there. Be creative, try to carefully remove the donor roof. Sometimes it's easier to cut along the roof structure on the door roof at the drip rail, or cut the roof on the existing vehicle and leaving the existing spot weld flange at the drip rail. It's difficult to remove the spot welds on a drip rail- try to leave it in place, cut the roof off with a sawzall and leave the flange on the vehicle. Follow me here? Bill