Tater , these old stovebolts are often seen cracked along the water jacket at the base of the cylinders ,, they will continue to run for years with a little sealer applied ,, say ,, some JB weld applied to the outside , or some Chemi Weld in the radiator .
I welded the block in my '39 truck once ,, drained the water out , drove it over to the workshop , had the block stinkin' hot , got the arc welder out and stitched it up , made a heck of a mess
tossed a can of ChemiWeld in and continued to use the truck for another 60,000 miles .
If all your frost plugs are rotten , then the block is maybe heavily corroded and sludged up inside too , I believe this is when that crack eventuates ,, Pull a frost plug and see what it is like inside , maybe flush it out with the hose , but most of all "Don't Panic"
