350 Engine Identification

[Eotku]

I bought a 1970 Chevy Blazer and I am pretty sure the motor isn't stock but I am having trouble trying to ID the small block motor that is in it. It has the 5/8 taper plugs (which is why I know at least the heads are newer). The stamped VIN numbers on the block looks like some numbers are inverted. I've been looking on the internet and am having trouble figuring this out. Number appears to be V0917CKS but at least the 1 and maybe more are inverted. Anyone have any guess on what engine I have?