After replacing the engine, it will crank over, but does not start?

Hello, have you checked the crankshaft sensor to make sure it has its 12-volt feed, Ground and Signal? You can even just test this with a 12-volt test light. Key On engine off the light green wire should have 12-volts, you can use the yellow/black wire for a ground for the test light since it's the sensor ground, which will take care of testing both wires. Then on the dark blue/white wire you should get a flashing test light while cranking the engine. If everything checks out, take the sensor out and make sure the gap for its trigger wheel isn't damaged or the gap is incorrect.
Does the check engine light come on while you're cranking it over?
If you replaced the crankshaft sensor there should have been a sticker on the end that you left on and it verifies the gap is correct. If you take the sensor out and the end is all scratched up, it might be an incorrect sensor. Also, did you do the crankshaft variation learn procedure? And what code are you getting on your scan tool?

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester