What is the experience of your father with photography? Does he have a SLR camera (or had one) ?
If this camera will be his first SLR, I would go for the K-r. A simple entry level SLR which is quit easy to use. If your father has previous SLR experience, he may prefer the K-7. (This is what I would do for my father.)
Both the K-r and K-7 are good choice. The K-r has excellent IQ incl. at high ISO. The K-7 is WR, has more controls incl. dual dials, a better viewfinder, the body is sturdy and the handling is superb. IMHO, if you do not need high ISO, the K-7 is the better value for money.
In any case, do not forget to add a good quality card (eg Sandiosk Extreme III 8 Gb) and a carry bag (eg toploader bag). The camera is no use without card and your father might not take it out without a bag.
Hope that the comment will help...