i thought that the rigid lines were more secure on the ends than flex, which is why the C/S prop governor uses rigid for the 600(?)psi line to the prop.  mid-span support(s) is usually simple.  does the rotary oil pulse pressure dictate a steel line?             kevin   [years ago when i made up braided oil cooler lines for my O-320 we used corps of engineers test equipment- could test in excess of 100,000psi, not that we tried it !!!]