At least 40, preferably 60; it would be nice to get some old non-NHL Finnish players like Lasse Oksanen, Jorma Valtonen, Veli-Pekka Ketola (though he did play in the NHL a little), Matti Keinonen etc. at least into the discussion, and I'm not sure if anyone of them is top-40 'material'.
I would think that the top 30-40 would be heavily 'populated' by Russian and Czech/Slovak players (and some Swedes), so I prefer 60 or 50. I admit, though, that I may not have very realistic picture of the project at the moment (since I haven't made or even thought about any lists yet).
Of course, then there are also some 'modern' Finnish players like Ville Peltonen and Raimo Helminen, who were WHC/Olympic stars in the 1980s and/or 1990s/2000s - and probably even more so than their Finnish predecessors - but it's all very hard to judge right now how they compare to, say, Venyamin Alexandrov and Alexander Almetov.
Actually, I don't even know how e.g. Peltonen and Helminen compare to the aforementioned '60s/'70s Finnish legends. It seems that firstly one would have to do some sort of top 10 list for every true hockey nation (or top 20-25, in the case of Russia at least), and only after that one can start to compare players from different nations to each other. It'll be tough and tricky... but maybe worth it.
Heh, I don't mean that I suddenly had this revelation, "hey, this will require a lot of hard work", but it will be very tough, when you really think about it. We'll have to have an extensive preliminary discussion about e.g. how different domestic leagues/international tournaments and their stars in different times can be satisfyingly compared to one another.