The RP105D from CMI is a pulley that is as serious as you are. Were talking 20,000 pound breaking strength with 5/8″ rope capability. The extra large rigging point accepts the largest carabiners–two of them. The extra wide, skirted sideplates fully enclose 5/8″ rope.
Stainless steel sideplates, two 3″ aluminum sheaves, bushing, and stainless steel axle.