I'm sure they would fit, but wouldn't springs designed for a v6's weight be a bit weak for the weight of a v8?
About 20 years ago I had put truck springs in my Mustang LX to firm up the ride and it worked. My friend wrecked his Mustang GT and convinced me to swap them out for his GT springs. Well, the ride was TERRIBLE, must firmer and better handling with the truck springs than the GT. FWIW, I know that doesn't have anything to do with v6 vs v8, but it was about springs...lol