The Bob Gumm catalog as well as a couple of posts recommend only using these headers with side mounts. (I don't like the side mounts because of the potential for frame spread. Also front mounts add structural rigidity while not spreading the rails).
I do know that the typical Transdapt / Hooker mounts front mounts locate the V8 towards the passenger side. I'm guessing that this is done to clear the steering column in combination with headers.
Is anyone running Don Hardy/Doug Thorley headers with front mounts? What issues did you have the combo, if any?