I think you're mixing up lower o-rings with the fuel rail insulators. The lower o-rings go between the injector and the inside of the rail. These will be new-style due to your 740s.
The lower fuel rail insulators go between the fuel rail and the lower intake manifold. These will most likely be old style, as I think its more likely for someone to put in the correct rail rather than machining their lower plenum. Could be wrong, though.