Gunsaholic:
You are very close to the truth. Despite what some concoctions are avowed to do, 100 years-plus of soaked-in oil and solvent is virtually impossible to remove from a stock head. The "best" that can be done is to get the surface oil out with solvents such as you mention. But the trade-off for that is a degradation of the old wood fibres through drying and softening. After all, it's just cellulose. And you're dumping nasty chemicals on it.
Result: A presentable stock head that may or may not be any stronger.
The important thing to remember is that certain portions of a gun cannot be "restored." They can only be cosmetically refreshed. And in some cases, that may be enough
