Problem with a scrapyard box is you do not know in what state it is, and you could drive 150km and it could go again, or you could do 150,000km without a whipser.
Resale value will not be effected that much, as resale value is already in the tank, meaning the car is worth very little right now, so you wont loose much additional, you dont even need to declare the swap,
In the long run, you need to decide, if you want to increase your grin factor, go with the manual,