Two things come to mind from your description, Mike.

First, if you loosen the delivery line at the injector and crank, you should see fuel leaking out there. I'd confirm this at all injectors. That would tell you whether the IP is functioning at least somewhat.

The other thing that concerned me from your description is the leaking new clear plastic fuel lines. Air is the enemy of IPs. Anyplace that leaks is also an air entry point. Whether the bubbles are small or large, until the air is bled out I wouldn't expect the engine to start. That can take lots of cranking (with the injector lines loosened first).

A resistance check on the glow plugs from the unplugged harness connector at the GP relay would be a good idea, also. I think it was 0.6 ohms but don't recall.

Best Wishes,
Bruce McCreary
Snowflake, AZ (6000 ft elevation, yes it snows)
'85 300D 170K