I just have a hard time believing that the rings suddenly crapped out all at once. Usually rings give out slowly, because they wear slowly. Gradually your vacuum pressure declines, the compression declines, and your performance reflects it. But in your case, it seems as if something attached to the engine is the cause of the problem. Whether that is a gaping vacuum leak somewhere, or a jumped belt, I suspect something OTHER than the B230F being at fault. The timing belt is a simple check. Since the vacuum system is pretty basic (except you can't really see in the booster) you'll get a good idea of what is going on there as well.

It seems to be a common opinion here that there is something ELSE causing your problems. Believe me, you CAN blow a B230F, but a well-maintained one is one of the most "indestructable" engines around.
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1992 940 wagon, low miles
as well as others.