The compression readings are way too low. The general rule of thumb is 20 X the compression ratio and in this case the ratio is 9.2. It will vary a little depending on altitude, barometric pressure, etc, etc.
Even a high mileage engine that is in good shape should carry about 180 PSI.
If the engine was actually rebuilt and that story is not a bald-faced lie then something has happened to it (overheated, etc), the engine was flogged into the pavement after the rebuild, or the rebuild was not done properly.
Run a wet compression test on it; meaning give each cylinder a small squirt of motor oil before you test it. If the numbers jump from 140-150 up to 170ish or so then there’s a piston ring problem.