I bought some braided rubber hose from Aircraft Spruce to use for the crankcase vent plumbing. Just looked, and they have something called Stratoflex 11 that looks like what I got. Available with large ID to fit this application.
https://www.aircraftspruce.com/catalog/pnpages/6000-14.php?gad_source=1&gad_campaignid=21252140130&gclid=CjwKCAjwjffHBhBuEiwAKMb8pABfYaVqQHjd3kTIyPoG OHNbe7XCeRyPEYkoAlz-Ur3Rlh6IGCZ9ihoC0h4QAvD_BwE