I have been thinking that game could be used to run a lot of classic content and I looked at the stat block and it would be a pretty straightforward process to convert a lot of old monster stats, but how would you go assigning saving throws?

That's actually an excellent question. 

I need to write the conversion guide to existing content ASAP. There are a couple of points that need attention there: first being the Saving Throws that are a "how hard would it be to shake this opponent with this approach". Quite straightforward, but the scale needs to be written out. The second point that needs to be gauged is Armour Class. Whereas many other games have a super powerful AC available to some opponents, in TDB, I probably would be a lot more generous towards the players. Probably not exceeding 19 on any single creature. Combat is deadly, even to the most horrifying of monsters.