Check CAM timing
I have done some additional study of the wiring diagrams. Personally am perplexed by your symptoms. Since you have asked for an educated guess, here goes my attempt to knock this one out of the park.
Refresh and go back over the details. No fire at all from the Right side. Some kick back during starting. Back to the basics. Fuel, Air, Spark, Timing (FAST).
A dynamic compression tests is OK. This would rule out valve and cam issues.
Previous posts state that you do smell fuel. This would indicate the fuel injectors are working.
Cylinders 5-8 are working. In addition, the PCM is communicating with the scanner. IMO, this would rule out anything but a one in a million PCM problem.
We believe that the COP’s are firing. What we don’t know is if they are firing at the correct time.
This gets back to timing. Let’s look at the things that could cause timing to be off on a complete bank. One thing that comes to mind is CAM timing. Since a dynamic compression test is good, we can assume the mechanical timing of the CAM is good.
But what about electrically? What if the CAMs themselves are timed correctly but the CAM gear is not? There is a raised piece on the CAM gear that is used to tell the PCM the position of the CAM (CAM sensor). If this is not in the correct position in relationship to the crank position sensor, it seams like this could cause some real problems.
Who timed this engine after the re-build? Were the recommended procedures followed? Were the correct tools used to hold the CAM and crank shaft when the chains were installed?
If it is NOT the CAM timing, let’s concentrate on the things common to the 1-4 COP’s. Splice S171 (engine, top, Right) supplies power to the Right side COP’s. However, unless something happened to damage the harness, a splice failing is a long shot. However, it is worth investigating.
The next thing common is connector C133. It is a large square connector located engine compartment, right side, rear. Your previous posts stated corrosion in this connector. CLEAN, CLEAN, CLEAN and CLEAN some more. Use electrical cleaner (brake cleaner not recommended). Another option is to use MAF cleaner. Afterwards put some dielectric grease on it.
I have some diagrams that may be of help.
<cutesy quote for the day>
Remember, there is no elevator to success. You have to take the steps.