[bigblockv6]

Some later 401 engines came with the 8 bolt crank too, you want the 6 bolt crank so you can use a 305 or 351 flywheel from a pickup truck. The good news is the 305, 351 and 401 engines all have the same stroke so you can use a crankshaft from a 305 or 351. The big difference is 305 and 351 crankshaft are cast Armasteel while the 401 crank is a forged. In a light duty application that should not pose a problem. That 401 appears to be locked up but doesn't necessarily mean it's the bottom end, moisture getting inside the cylinder bores from the intake or exhaust manifolds can build up a layer of rust in the cylinder walls then locking up the pistons.