Found 70 340 engine in original paint, has J heads, lower pad is stamped B425xx7. Probable a Cuda 340 engine by the VIN. Nothing stamped where the two x's are, just blank in those positions, and it is a factory stamp. Stamped on front of block is F340P32620298. Early July of 70 assembly date. From Washington state the Tri-cities area. Is this your engine?