I'm looking for some historical results (more complete than possible) of cross country skiing. The races are: - 50 km men Finnish Championship (Kuopio) 1972 …

The best books to look for older information in, are the Mitä Missä Milloin – kansalaisen vuosikirja –books. They are published every year on the events of the previous year. So information regarding cross country skiing on a Finnish championship event in 1972, can be found in the book’s sports section of the following year, Mitä Missä Milloin 1973. Some of this information can also be found on Wikipedia.

Men’s Finnish Championship’s 50 km event in 1972 (Kuopio):
First place Kalevi Oikarainen (time 2.44.10). Second place Ahti Nevala (time 2.46.45) and third place Reino Tamper (time 2.46.53).
http://fi.wikipedia.org/wiki/Hiihdon_Suomen-mestaruuskilpailut_1972

Men’s Finnish Championship events in 1973 (Kurikka)
15 km
First place Juha Mieto 45.17. Second place Raimo Lehtinen 47.32. Third place Eljas Nygård 47.47
30km
First place Juha Mieto 1.30.23. Second place Hannu Taipale 1.31.39. Third place Raimo Lehtinen 1.32.31
50km
First place Juha Mieto 2.53.28. Second place Jorma Kinnunen 2.57.13. Third place Teuvo Hatunen 2.59.13.

I couldn’t find any information on a Puijospelen race that’s 50 km long for that year (1977). If you mean Puijon kisat, then the last time a 50 km race was skiied in was in 1976. More information can be found in Finnish from Puijo portaali, were you can find some historical information on the races.
http://puijo.kuopio.fi/1970-luku

Men’s Finnish Championship in 1978 was in Jyväskylä on 20.21.1, Lahti on 28.-29.1 and Yllästunturi on 25.-26.3. Tampere didn’t host the championship games that year.
First place Juha Mieto 42.56,03. Second place Pentti Vahvaselkä 43.31,67. Third place Matti Pitkänen 43.38,27. More information about the game can be found on the Wikipedia page
http://fi.wikipedia.org/wiki/Hiihdon_Suomen-mestaruuskilpailut_1978