You are probably watching, DDSpeedShop is building a 2 door biscayne,big block. If you arent, may want to go look.
He has done a pile of tri-5 chevys. He starts by comparing roof lines between 2 and 4 doors. Somewhat of a hack but gets the job done.
You are right. I watched him do the 4 door to 2 door Biscayne transformation. He is a bit crude, to say the least. I bet he buys Bondo in 5-gallon buckets. But he does get the job done. I like watching him.