If originality is really important, make sure the 289 you get is a "K-code" motor.
That was the 271 HP version of the 289, had a special crank with a front conterweight, and Shelby "Shelbyized" it like he did the 289 in the Mustang GT350 up to a bit over 300 HP (IIRC the number was 306)...tri-y headers and an intake manifold/carb, perhaps a cam (I can't recall whether or not that was one of the changes).
For originality sake, the appearance of the engines is important, too...all of us small block guys who run cast aluminum valve covers that say "Cobra" lose the match to those who run stamped steel valve covers with long breather tubes. There is more....much more.
For the 427 version, only an FE will do if you are looking for originality, and if you really want to be authentic it must be a side-oiler.
Lots of people think the 427 version always had 427FE engines, but in actuality at least half of the big-block cars had 428CJ engines....visually undistinguishable from the 427 side-oilers.
"Originality" didn't last long with these cars, though...many were quickly modified and upgraded...the 260 Cobras almost all had 289 engines swapped in soon as they became available.
In the end, it'll be yours, make it look like YOU think an original would look. Not long ago we had a "barn find" thread, about an old red 289 street model, the owners displayed it at concourse events without even cleaning the rust off the chrome air cleaner...it's not always about looking perfect with these things.
How about gumballs? Rookie stripes over the drivers' side fender.
Lotsa "original" looks...pick one, any one, go for it!
Cheers!
Dugly
