you might want to check SB2 chevy. I think the crank snout is big block chevy and seal is big block ID and small block OD. crank gear bbc ID and sbc OD. Not positive, but I think so. Just a thought
there are spring company all over in big city, try yellow pages. in kansas city try american spring co. if you don't mind spending the money, air bags are great. air ride tech has a kit for 58-64 chevy that's great.