Volume 1, Issue 2 of "AMA Racer" newsletter includes some excellent action photos featuring Penton motorcycles and POG'ers. Page 4/5 is a beautiful, large image of (I believe) Ernie Phillips.
Also, page 13 contains another nice Penton/POG'er race photo, although in this case I do not know the rider's name.
And finally, page 19 contains a great "mud" shot of friend-of-POG, Bob Wark, boogying down the trail on his WWII-era BSA B40. (Hope I got that all right).
I'm not sure how you go about getting these full-color newsletters. I'm not currently an AMA member, but I know this is NOT the AMA magazine, but rather a different publication altogether. I picked up my copy at the local motorcycle shop, where they were just lying on the counter.