Thanks to blog reader "MM" I am now aware of that more Finns than I had imagined served as volunteers in Vietnam, and not only in Special Forces like Larry Thorne/Lauri Törni.
Seppo Hurme was a helicopter pilot in Vietnam with HMM-361; Markku Kanervikkoaho secured transportation; Timo Peltomaa was a medic.
There is a book about Finnish volunteers in Vietnam, Sinivihreat Baretit (Bluegreen Berets) by Kari Kallonen published in 2006. As I do not read Finnish, sadly, I´d like to know the total figure, how many Finnish volunteers were there all in all?
MM also suggested checking out the Australian War Memorial as it has several Nordic names. This is its online directory.