If it is a 71 block or earlier you have one of the more desirable Windsor blocks you can get, if the engine is apart have a look at the rods. The last 1971 351W motor I took apart had C9AE rods in them which is the better late sixties rod, they are slightly stronger. By a stroke of luck the heads were C9XX also...WOOHOO! Other than these items the blocks are mostly the same with only the bore casting getting a little thinner later on. Check your valve seats, some early heads had a tendency to crack in this area.
Have a look, good luck!
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