I have a backhalved 88 camaro.What length and springweight should i look for when i order.

Or if someone here has a 4link,and coilovers,etc... i can do that as well

 

Spring selection is dependent on application and driving style, springs like sway bars are tuning tools. With the car backhalfed I'm assuming drag racing is the intended use of the car? Detroit Speed offer a 4 link kits for our cars and they use 275lb springs with 10" free height.
1988 Chevrolet Camaro Rear Suspension Quadralink & Decalink Parts - Detroit Speed

 

It might go down the track once for the bucket list.

Intent is a cruiser.