Just bought an '81 El Camino. Originally had a 6 cyl but now with a SBC. Supposed to be a 350 but I'd like to know for sure what it is. I've checked all the web sites I could find but have not found matching block casting number/block stamp.

Casting number: 8970010 (First digit IS 8, not 3.)

Stamp: V0421TAG Can't find "TAG" in any list.

Don't have a VIN.

Any help would be great.