In the past, I was pretty sure Viren used auto-transfusion, which started with Finnish runners and at that time (beginning '70 years) was considered not as doping, but as "very advanced scientific help" for endurance events.
So, first thing : I never can call "doped" all the athletes using this practice, till when was not outlawed (1985), exactly like I don't call "doped" all the throwers using steroids before officially were banned by many international Federations of different sports.
I don't discuss IF these practices gave advantage in the performances : I only look at the moral reason because athletes were allowed to do this, when steroids and autotransfusion were considered legit ways for training more and having better results.
I remember, the first time I went US in 1972, that it was possible to find, and to buy, steroids without any prescription, since were considered at the same level of vitamins and all the supplements used today. So, for the users, steroids were simply "supplements", and in their mind the idea to have some benefit is not different from who wants benefits, today, using legal supplements.
Apart this "phylosophic chapter", everybody in the Athletic World knew Finnish athletes had, in that period, blood manipulation using their own blood.
One of the scientists working in Yivaskila was the italian Carmelo Bosco, my mate in Turin University before going to study physiology in Finland.
Together with scientists like Vikho and Komi, they were a Group studying especially the muscle fibers in all their reactions, and were linked with the scientists studying the "aerobic" side of the performances.
According to the stories of Bosco, all the Group of Finnish top runners, training under Sinkkonen, used the auto-transfusion : Vaatainen, Paivarinta, Maaninka, Vasala, Vainio and Holmen (European Champion 1974 in 3000m).
Also in Finland, however, many were not sure about the use of this practice with Viren. Some year ago, I had the opportunity to speak directly with Lasse, and he clearly told me that never used any blood manipulation.
I'm inclined to believe in what he told me, for a very simple reason : looking at the Italian experiences with Conconi, I can say that some athletes were able to win important medals using this system, some other won without using, but, especially, some other was not only "not responder", but was damaged for his future career, without having any improvement.
In Italy we had some case, like the swimmer Franceschi, who used the auto transfusion before Los Angeles '84, achieved one of the worst results in all his career, and never was able to go back at the same level after Olympics, in spite of very hard training ; or like Salvatore Antibo, who improved his performances dramatically after quitting this practice in 1985.
Maybe Viren never accepted to do any blood manipulation because had a very high "ego" and self confidence, and his main motivation was to win with his own strength (like Gelindo Bordin or Shaheen, who Always refused any medicine, also when sick, saying "I want to see who is stronger between myself and the sickness") ; or maybe he had some test before using, discovering he was a "not responder".
For all these reasons, I strongly doubt blood doping can have the same effects with different athletes. And, in any case, don't forget all these practices had their max spread BEFORE the massive use of training in altitude : Finnish runners never went altitude, the same Alberto Cova and Antibo (before 1985). From 1986, Antibo started to train in altitude, such as always Bordin did, and improved a lot without using any other system.
So, my final answer is : no, I think Lasse Viren never used some blood manipulation.