GREAT SUCCESS!
I got the short block on an engine stand and drained the oil. Took the pan off, looks very clean. ::sigh of relief:: I decided to give it one more try and grabbed the 24" breaker bar. To my surprise, it spun over with ease. A few of the lifters were collapsed and cupped on the bottom. But, overall it is a good base for what I need.
The plan is to get a cheap rebuild kit: gaskets, rings, bearings, freeze plugs, cam and lifters, and a timing chain. I'll have the block boiled and new cam bearings installed. Then hone the cylinders and clean up the crank. It won't be a precision rebuild, but will get the car running and me in the driver's seat much quicker.
I had read that an L48 found in B body cars had 2 bolt mains and cast crankshafts, it turned out to be true in this instance.