Mercruiser 5.0 has fuel, compression and spark but won't start

Any help is appreciated. I've hit a brick wall. The starboard runs fine so I've swapped the following parts for comparison:

ECM

Coil (in case it was weak spark)

Cap and rotor

Installed a new battery as the starting battery on the port side was bad. Removed a valve cover to verify valves were opening and closing. Fuel pressure is 46psi. Removed fuel rail to verify spray pattern and operation. Sprayed with starting fluid and it won't even cough.

What should cranking speed be and would slow cranking effect the engine not even trying to start?

Could it have jumped time and if so is there a way to check without removing the front cover?

Please help, I'm out of answers

Doubtful that it jumped time. If it jumped time it would still try to start or run poorly. How did check the strength of the ignition spark. Did you use a spark gap tester?(Available at your local auto parts store for a couple of $$)

Yes I checked the spark with a spark tester, compared it to the one that runs and they appear the same

What are the compression numbers for each cylinder?

Type of motor, year, serial number all help.What was the motor doing before it stopped working? Prior work performed?Have spark means the cam is still turning, also you said the rockers move also. Verify that you are actually seeing gasoline in the fuel rail and not water.Remove the spark plugs to verify no water in the cylinders. Yes, you can crank a motor over with enough moisture to kill the spark plugs.Per Chris, a compression test is next.