I assume this is a sohc 12v engine, with a distributor. If it has spark and fuel, it has to be timing or compression. If it's compression, it will turn over too fast. If it's timing, there should be a few combustion events, and maybe some pops and backfires.

Pull the #1 plug and turn the motor by hand until you feel pressure on your finger on the plug hole, then turn the motor further until the crank timing mark is at tdc. Remove the distributor, and align the cast mark on the housing with the mark on the shaft above the gear. Holding that position, reinstall the distributor with the clamping stud centered in the adjustment slot. Note that the internal dist cap contacts DO NOT align with the external plug wire terminals. The distributor should now be aligned with #1. Now, ground the timing adjustment wire near the brake booster, a single wire with a terminal end, and set the timing with a light. The engine should fire even before the timing is set precisely. The engine does not have to be torn down to check cam timing, just align to tdc as above and pull the cam sprocket front covers to see those marks.

The mechanic should have known this...