Help needed changing 996.1 engine harness

[P210Driver]

Is a wiring harness change possible with the engine still installed?

I have a 2001 Carrera cab. it's throwing a P1229 which is a short to ground on the #3 injector circuit. The engine seems to run ok, it's a bit rough when cold and at idle. The previous owner has hacked the wiring harness; as far as I can tell the #3 injector wires now come directly from the #5 injector. The wires are spliced in a few inches from the #5 then run across the top of the engine and directly to the #3. There is no sign of the original wires from the harness near the #3 injector.
How does that even work?
The wiring diagram shows that the injectors share a common ground but the other wire connects to a separate valve for each injector!

I picked up an engine harness on eBay and was planning to install it to resolve the issue but I can't seem to get access to all the connections even after dropping the engine the prescribed 4cm as described in the injector change procedure. Hopefully access may be possible by removing some of the engine accessories I just don't want to start pulling stuff off willy nilly if there is no chance.

Any help or suggestions would be greatly appreciated.

[JFP in PA]

Not really.

[991gts6s]

super easy to drop tho..

[P210Driver]

So it's unanimous then...I have to remove the engine but its dead easy huh:-)