If it's that gummy, you're wasting your time trying to clean it up in the frame. It's your time and money, obviously, but doing a halfway job is not something I'd reccomend. There are dozens of places you won't be able to clean, and as soon as the oil hits the crud, it will circulate it all over ther new parts.
BTW, splash oiler engines also have an oil pump. The main bearings get pressure-lubricated. The rods have dippers bolted onto the bottom and they dip into oil-filled troughs in the pan. At higher speeds, the tubes that fill the troughs squirt oil directly into the rod dippers. Any engine newer than 1953 should be a full-pressure design with oil passageways drilled through the crankshaft to supply the rods with pressurized oil.
Jerry
