Wiring Harness Plastic Sheathing? Options

[TINKERGINEERING]

Currently working on the wiring harness and found a couple wires in desperate need of replacement but they go through this plastic sheathing on the harness. Has anybody replaced wires through this sheathing? Should I just pull the wires out and try and jam them back in? I was also thinking I could just replace the sheathing, because it is 50 years old now, but how would I put new sheathing back on?
Thanks so much

[Chris914n6]

There is no reason not to modernize it. A split loom of your choice and TESA tape for the ends. You are likely going to add wires thru the snorkel at some point.

Gander under the hood of a modern car for reference.

Factory sheathing was originally soft and flexible. Not so much decades later...
you could probably heat it with a hair drier to soften it enough to slide it off in one piece if you think you might want to use it later.