Some initial thoughts as to design parameters.
1. Keeping to stock lengths means you can store as delivered.
2. Material visible from the ends is easily to identify.
3. Separate storage for off-cuts keeps the main rack tidy and splits the problem into two versions with different issues.
4. Pulling out lengths horizontally is easier than vertical lifts especially in the larger diameters.
5. Long racks of long stock accessed from the end can utilize space behind machinery and save space.
I would keep the long rack and solve the off cut issue with other storage.
regards Martin