Dart 1969 - faster 1/4mile

Whats the diff between these two 4.10 Dana 60 gears from Richmond? One is 8620 and the other 9310 steel? The cheaper one is capable of drag race at our hp and tq levels i asume?

Richmond Gear 69-0052-1 Richmond Gear Ring and Pinion Sets | Summit Racing

Richmond Gear 79-0011-1 Richmond Gear Pro Gear Ring and Pinion Sets | Summit Racing

Nitro Gear 4.30 any good?
Nitro Gear & Axle D60-430-NG Nitro Gear and Axle Ring and Pinion Gear Sets | Summit Racing