One more for the list, pull a freeze plug or more to really flush out the block. Did this with a nice low mileage car years back and the darn block was packed with rusty crud, was quite a job just digging and flushing it all out.

It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed