A generous "L" strut can mean many different things and may not mean that there is enough for graft material. Your surgeon might know .
You are asking a very basic question about supply and demand. The answer depends on the amount of cartilage left in your septum and what will be needed for your revision. Don't be concerned; there are other sources of cartilage available, such as your ears.
Hard to know from the info you have provided alone. If your nose needs to be significantly enlarged, more cartilage than the septum and ear may be needed. Your residual septum is unlikely to have much left but both ears may yeild enough. Otherwise your choices are rib cartilage or an implant. Ask your surgeon for advice. Good luck.
The correct answer depends on how much cartilage remains in your septum and how much cartilage you may need to affect the revision rhinoplasty changes that you desire. Your surgeon can best recommend which source of cartilage is required. Septal cartilage, rib, ear or irradiated rib cartilage options may all be considered, depending on what is needed in your particular case.