Rear ride height

Installing longer rear shackles will raise the back end of the car. But you need to add a lot more length than you'll get in height, and it's not great for the ride.

Was pretty popular in the mid to late seventies, along with air shocks. Neither are a good way to raise your ride height.

But, I'd be more concerned about the change in ride height. Have you driven the car at all? If you haven't, it may settle a little. If you have, I'd be concerned that the shocks are too short and are keeping the springs compressed.

Even if the shocks are correct for a stock car, it doesn't mean they'll fit. If the springs are raising the car higher than stock you may still need longer ones.