Don't trash the cracked block- - - -it can probably be repaired by someone willing to put a little time and money into it for a numbers-matching restoration than won't be run hard. I've salvaged a block that survived a pretty massive blowup on the track- - - - -it swallowed a valve at the end or a straightaway and hydraulic-locked from about 6K RPM because the valve poked a hole in the cylinder head and flooded the engine with coolant. One sleeve, new connecting rods, pistons, camshaft and heads, and it went into a street machine. We didn't look too closely for cracks, but that engine ran for several more years.
Jerry