DPI is not a 'setting'. DPI is a simple calculation - "Dots per Inch".
So, for an 8x10, at 300 DPI, that would be 2400x3000px, or 7.2 megapixels.
The K-30's highest ability to print at 300 DPI (16 mpx) would be approximately 16.4 in x 10.8 in. For your reference, the K-3 allows up to 20 in x 13 in printing at 300 DPI. Of course, you can go much larger than that, but the density of your dots (DPI) and thus the quality, goes down. When viewing from afar (even billboard size and distance) the resolution becomes less of an issue. It's more so when you have a large print, say 5+ feet tall at the bus station, that you view within a few feet, that you need uber high resolution (medium/large format or stitching, in which case if you stitch, your camera DPI is infinite

).
Having your camera at highest JPEG setting will increase the detail as compared to the lower settings (and processing your only DNG raw's even more so), but it will not change the DPI. a 10mpx image from a cell phone, from a point and shoot, from an APS-C camera, from a Full Frame camera, from a large format image scanned with a scanner at 10mpx -
all at 10mp will all have the same exact maximum print dimensions at 300 DPI. Now, when you examine all of those prints, the quality will surely differ, especially the cell phone/point and shoots from the much larger sensors, but the total number of dots per inch will stay the same.
Hope this helps.
-Heie