All one needs is a HP stamped block from 1970 (within the right casting date to build date), a warranty block with no VIN on it would be ideal. There is no "V" code blocks as six pack engines did not have anything stamped on the block to differentiate them from standard HP engines. The only way to tell an original six pack engine would to find one with the original VIN stamped in the rail and there is only one of them out there that matches the VIN of this car. Once you had a block then you would have to hunt down six pack rods and external balancer to complete the package other than the six pack carb setup of course.