Before you put much more time into it, determine WHY the radiator leaks. Did it freeze and break, or just rust through? If it looks bulged, I would suspect the engine is broke. You cannot always tell by looking.
Try getting a big funnel and bucket so you can get lots of water in fast, and overcome the rad. leak. Pull the heater hose just below the stat to "bleed" the system. When you get the block full, let it sit a bit, then check the oil and look for water in the oil.
After you do that, you'll have to pull the block plug and drain the water, as it may then freeze
