Here is a scape with the sort of rock you have. Think bigger if not this big.
Aquascape No. 3 - ADA 90P - Moss Canyon - Final Photo on 1st page
Like the rock with the substrate and the left hand structure is very nice but too small to be a main rock. The slanted rock on the right is distracting as it reflects light differently. Perhaps it is more effective in real life? Like the way you have placed the two groupings a lot.