I'd look for a large shank action. They will be tough to find used, as that will limit you to basically WSM actions. The good news there, the bolt face will be correct.
Why not buy a cheap new Savage and sell the barrel and stock? Probably get $25+ for a plastic stock, up to $100 for a laminate, get at least $75 for the barrel (depending on contour etc.). If you can find a new action with the correct bolthead for $400, that would give you the action/trigger for $300 or so.
A small shank action will work, however you will probably need to change the bolt head (another $50 or so).
Depending what you plan on doing for a stock, the following rifle would be a perfect starting point, the trigger should be good, the stock is usable and all you'd need to do is change the barrel. The nice thing about the Model 12 is that the Accutrigger has the medium springs in it, so its ready to go. Most of the other Accutrigger's have heavier springs than I care for. The target action Accutrigger has the lightest springs.
GunBroker.com guns: Savage 12 12BVSS Varminter .300 WSM (item: 88071599 ends: Dec-23-07 08:17:06 AM)