IIRC, the 7" version even at 4.30 was actually the short version- the 12" was about 7 minutes or so.
One thing many forget tho' is that in general, 12"ers were never meant to be played all the way through - they were meant for mix wizards to do their stuff with.
Just think, somewhere in New York or LA at some point , people were probably dancing to Curtis one minute and Anita Ward "Ring My Bell" the next, not realising the change point