HELP0... which direction is better?

I bought my '74 Duster for $2k. It has zero rust. None. And it was even sort of running/drivable when I bought it. From the sounds of it, you have more than $2k worth of sheetmetal to buy, not even including the cost of labor.

The '73-'76 Dusters don't have much for value if they aren't 340 or 360 cars, and even then those are worth quite a bit less than a pre '73 340 car. I would part the one you've got and look for another.

One question, why do you want to cut the top off? Are you talking about just putting a snakeskin top on another car? Or cutting off the entire roof? Either way, I don't think I'd do it that way. It's unlikely you'll be able to get the vinyl off in one piece, and if its for the sunroof it would be far easier just to swap the sunroof itself.