>Was the 400 available from the factory in a 1972 Ranchero
>500?

I have the Ford showroom brochure right here, and it says that the options were 250 (inline six), 302 2V, 351 2V, 351 4V, 400 2V, and 429 4V. Several 351 motors were available, including the 351CJ, the 351C 2V, the 351C 4V (higher compression than the CJ!), and one or two versions of the 351W.

The 400 was rated 172 HP @4,000 RPM, and 298 ft/lbs @2,200 RPM. It had a compression ratio of 8.5:1 (I have also seen this reported as 8.4:1 but it really does not matter)...