aussie 408 combo

1.6 rockers will marginally change the effect of the camshaft as if it were slightly longer in duration. This means it will move the RPM range up slightly however with a hydraulic roller camshaft like the one you suggested it will cause any potential for lifter pump-up to occur earlier in the RPM range.

So theoretically to get the most gain out of 1.6 rockers they should be combined with a lighter spring/valve. (beehive springs are good)

Or go solid roller.