Before you look at new engine, I would consider checking that your crankcase can still breathe. If your PCV valve, for whatever reason, plugged off, and your valve covers are closed (no hole or breather on them), it will shoot the crankcase pressure out of the only place it can: the dipstick, and the hose from the valve cover to carb to burn blowby vapors. If you discover your crankcase has ventilation, and it is still acting up, well, I am out of ideas. An engine with shot rings will burn oil, with shot valve guides especially at start up. Shooting oil out of dipstick? Excessive crankcase pressure.