At this late stage, the boat has left the harbour.
Nothing will make these flowers any bigger/denser at this stage of life, they are closer to the end than they are to growth, all they have left is a bit of further maturing, but all growth has basically stopped and no amount of light or food or anything else will make them much bigger or denser.
Sorry if it is not the news you want to hear, but it is the only realistic answer to this question. You may get a little extra "swell" or a few extra calyxes, but we are talking a less than 5% increase in measurable size/weight. 
A 65 watt LED will never give you huge, chunky and super dense buds, it just doesn't have the strength.
Hope this helps,.........
Organoman.