Tim,
High ratio roller rockers will work very well with an A6 cam. I think you will see an improvement in both torque and power. With a similar spec. cam, high ratio rockers etc. my old 1700 made 175bhp (dynoed) on 45Webers, and 180bhp on TBs. You won't have any installation problems as the overall lift will still only be 11.5mm (similar to a 254)
Trust Dave...if he thinks it should work, it probably will!
Cheers,
Chris.