I'm not a plethora of Ford info, but I do know a little. Any of the blocks are fine. From a 68 429 all the way to the end of production in the 90s....whenever that was.
The important thing is the heads. Sounds familiar doesn't it? Any of the early stuff has the smallest combustion chambers.
Ford has easy to understand casting numbers.
C=1960s
D=1970s
E=1980s
Then the second digit denotes specific year. C8=68, C9=69, D0=70.
What you are looking for will be C8XX C9XX or the coveted (only because it "spells something) D0VE castings. That's for the 1970 model year. Or D1XX or D2XX. any later and the chambers do get bigger.
The dang best ones are D00E which are the CJ and SCJ castings. Then comes the cop stuff which is usually D0AB or D0AE - D2AB. In other words, 1970 - 1972. in 73 the chambers got a good bit bigger, although they were all still close chambers, so with the right piston any of them can get compression, the early ones have the better ports.
Distributors interchange between 460, 429, 400, 351M and 351C. Bellhousing bolt patterns and motor mounts interchange between 460, 429, 400 and 351M. This is why the 460 swap is so popular for the 78 and up Bronco and truck guys. Although I don't know why, because a well build 400 will skin a 460. Nobody ever liked the 351M or 400 because like the Chrysler 400 they never had compression. But they can be fantastic engines with a few mods.
