I guess that would depend on what you mean by 'worth it'. Ford didn't start using that motor in the Mustangs until June 1st of 64, so all of the stuff like the heads, fan, intake, etc... will probably be date-coded much too early for a Mustang. The hipo blocks that were destined for a Fairlane are easily distinguishable from the ones used in Mustangs, so, even though the date codes can't be seen without pulling the starter, a judge at an M.C.A. event can tell immediately that this is a Fairlane block. Or, at least, they should know that.
The only parts that would have a value much higher than you might imagine would be the main bearing caps. A good set of those will bring something in the thousand dollar range.
However, if you build that motor back to stock configuration, it will be a real screamer. They can buzz along at six grand all day long, and with only the most modest of 'tweeking' you can also have them putting out something in the 300+ HP range
so those, in and of themselves, makes it a really neat motor to have in a Mustang.