If it were me, I'd buy a case of Red Head A7 anchoring adhesive: https://www.fastenal.com/products/details/0228790
Get an engineer to do the static load calculations and design the attachment disk and bolt pattern. Weld a big disk with holes around the edge and gussets to the bottom of your pole. Drill however many holes of whatever size the eng says into the rock and put in some B-type threaded rod with the A7. Washers and nuts above and below the disk to level it. Pack underneath it with concrete if you want. Granite is a great base if it is flat and solid.
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