Several variables come into play, so difficult to say with certainty. Might be a good idea to try what you have first. Pay attention to function, reliability with ammo you plan to use, "feel" (or smoothness of operation), and ejection pattern. The rifle's behavior will often tell you what it needs for fine-tuning.
All that being said, it's usually recommended (if starting from scratch) to use an M16 bolt carrier and H3 carbine buffer, especially if the gas system is midlength. If using a rifle-length buffer system, the standard buffer often works fine. I like the Tubb / SSS flat wire buffer spring regardless of buffer weight and tube length.
Edit- leopard6.5 was faster on the trigger with a good reply. I'll leave my reply as is so that perhaps you'll recognize some similarities in recommendations.
All that being said, it's usually recommended (if starting from scratch) to use an M16 bolt carrier and H3 carbine buffer, especially if the gas system is midlength. If using a rifle-length buffer system, the standard buffer often works fine. I like the Tubb / SSS flat wire buffer spring regardless of buffer weight and tube length.
Edit- leopard6.5 was faster on the trigger with a good reply. I'll leave my reply as is so that perhaps you'll recognize some similarities in recommendations.
Drifter