Sorry to hear of his troubles. I have to say, I've been down that road and followed Dr. William Davis' Track Your Plaque website for several years due to 90%ile+ calcium scores starting in my mid 40's (and osteopenia) before giving up on him when he decided wheat was the source of all evil in the world of health. I thought I was eating a good (low fat) diet and exercising reasonably so the high percentile really shocked me. Still, I learned a lot from Davis and the more informed participants on his forum.
I'll assume that increasing his D3 by sun is a limited source for improving the D status. The half-lives of K2 in the blood are nowhere near as long as vitamin D. I used to take a combo D3-K2 (MK4/K7) daily, but now only do it in the winter as I can keep my D3 in the 40's with my pale skin and abundant sun here in Southern California most of the year. I make my wife take the D3-K2 combo twice a week year-round since she gets so little sun and SAD levels of fiber. I get lots of green leafys and eat a high fiber diet to help feed the gut bugs that make K2, so I'm no longer taking a K2 supplement. A standard dose of K2 is 100mcg but there are dosages available in the 1000mcg range, and clinical trials in Japan have used 45mg/day for osteoporosis with, apparently, no adverse effects. Chris Masterjohn, who I consider really smart about fat soluble vitamins, would advocate for a balanced Vit A/D/K, preferably through organ meats and sun, but he recognizes one's D status and response to dietary/supplement intake is highly individual. I've heard Masterjohn also caution against monthly dosing of D3 in favor of more regular intake more like what we were designed for evolutionarily.