I am having doubts that David Montgomery (drums) of the New York band King Harvest is the same person as David Montgomery (drums) of the UK band Arc. Anyone have any leads?

I know what you're saying but King Harvest seem to have spent most of their time in France : http://en.wikipedia.org/wiki/King_Harvest
Can't find much else and am not sure what the Australian drummer for Python Lee Jackson may have to with this... but he seems(?) to be the Arc guy
http://en.wikipedia.org/wiki/Python_Lee_Jackson

I've done the best I can with the lineups for that band. I'm pretty sure that the 1972/73 lineup should be different from the 1975 lineup, but there just isn't enough information online.

These are some fun links though:
http://cornell-magazine.cornell.edu/Archive/2002mayjune/notes/1960to1969.html
http://directmag.com/mag/marketing_crossover_dreams_2/
http://www.atnewyork.com/news/article.php/927521 ("I played with King Harvest...recorded in Paris...joined the Beach Boys to play piano. I had studied with Nadia Boulanger in the late 1960s and later produced records and music videos.")

http://www.classicwebs.com/kingharv.htm (lineups)

I think you're right. I asked Rod Novak from King Harvest. He helped me update the King Harvest lineups.

---

Do you know if the David Montgomery of King Harvest was the Australian drummer David Montgomery who played for a UK band called Arc?

I BELIEVE SO, SINCE DAVID WAS AUSTRALIAN AND WE MET HIM IN EUROPE.