8 x 10 is actually the most common size for a dining room rug....big enough for the chairs to still be on the rug when the table is in use and the chairs are being pulled in and out.
6 inches on the long end is a little tight, but IMHO, 6 feet for a table and pulled out chairs is tighter. My room is 10x12 (including the bay, so closer to 10x11 on the edges). The front legs of my buffet are on it, but not the back legs. I think the sizing on it is just perfect. Yours would be shifted three inches back from the bay window wall as compared to mine. Here's our DR with the 8x10 in a 10x12 (shared space with LR):
(edited to include pic without crazy paint swatches all over the walls)