man, I don't know where to start. I never caught what year SB you're dealing with. I believe there are two different timing covers with different timing mark loc'ns. There are also some aftermarket distributors with indexing different from oem distributors. There is also the oil pump drive indexing to check. Plus, it appears you have a multiple keyway crank sprocket. If you want to be 100% positive of the cam timing, I'd be inclined to dial the cam in, but I don't know if you have the cam specs or even know the manufacturer. Can the PO help with any details?