In this order, convertible, 2+2, and then the coupe .. the convertible will probably be left alone, while the 2+2 (correct name) will get the V8 restorod treatment.. Coupes, even with the V8 are only worth half of what a 2+2 goes for..
By actual book value the two are about equal according to OLD CARS PRICE GUIDE. So the 2+2 is catching up..
I have a convertible and a 2+2, and I don't buy coupes anymore after owning 4..
Classic V6 Mustangs do have a market, but they are not the more valuable ... period. The V8 '65 is more valuable if fully restored. The faster muscle cars are the ones that are selling now. No one is really looking for a V6 with under 180hp to collect. You can check the link below for more info.