I would be interested in documentation that indicates a top oiler 427 was planted in an original Cobra. Could be, but it's news to me. The 428 was used for awhile and then Shelby switched back to 427's (after customer complaints). At any rate the Cobra most of us emulate is the S/C, only 30 or so being built of the approximately 300 total count. S/C, side oiler, stick a fork in it!
"Rumor has it", my favorite saying when it comes to nailing down Cobra history, is that nine of the original cars (later models not early ones) may have had a center oiler.