As someone that has converted a '74 Duster into a '71 Demon clone, it's honestly not all that difficult. Obviously there are some differences to consider depending on the year/model being cloned or converted, but the majority of the conversion is just bolting stuff on (again, year dependent).
As far as the price thing, well, I know that I spent less to convert my '74 Duster into a '71 Demon than an equivalent condition '71 Demon would have cost. '74 Dusters are super cheap (highest production A-body model/year), '71 Demons are not. The entire front clip cost me $500. Even with the tail panel, rear bumper and brackets and tail lights, plus some of the extra goodies I threw on (scoops, '68 markers, the '71 doors I haven't swapped yet, etc) I have less than $2k into the conversion. Granted, I did all the work myself, so that's just the cost of the parts and materials. I paid $2k for the Duster, and even at the time there was no way in hell I'd have gotten into an equivalent '71 Demon for under $4k.
View attachment 1716431066
View attachment 1716431067
View attachment 1716431068
My '74 did have the frame mounts for the standard front bumper brackets though, so the entire front end swap was a bolt on. The rear obviously required a tail panel swap, followed by welding up the rear crossmember where the shock mounted rear bumper brackets went in order to be able to install the earlier rear bumper brackets. But none of that was particularly complicated, and the rear tail panel on my Duster was pretty banged up so a tail panel replacement was on the table already even if it had stayed a Duster. Like the new interior panels- I needed them anyway so buying '71 instead of '74 isn't extra (in fact, some of the '74 stuff isn't reproduced so going '71 is an advantage there)
And that's a consideration too, at this point these cars are pretty old. So hanging a new tail panel or even quarters on a car isn't an uncommon repair to begin with. Obviously there are cars out there that don't need their quarters replaced, but depending on the condition of the car the conversion isn't necessarily a whole bunch of extra parts. When my '72 Challenger goes back on the road it will look like a '71. But it needed quarters and fenders anyway because of the rust and damage to the car. So the only extra parts at that point are the header panel, hood latch and grille. Hell even the marker lights aren't extra, the originals were cracked and needed to be replaced so it just gets '71 markers instead of '72 replacements.
Depending on the built date on the '74 it may have already had the front bumper bracket mounts, so the whole front end is a bolt on. The rear is quarters, the tail panel, bumper and trunk lid.
