IMHO, it is not. 727 lines are 727 lines in any chassis. more W350 had a manual trans most likely would be my guess.

they may be pre-bent a little different depending on model/engine combo.

I have used the same 904 lines on 727 and vis-versa pulling a used set from the JY.

IIRC the lines on my 88-440/727 truck are from my 68 Dart 318/904 trans. also added the large truck trans cooler in the system as well.

I got the 8 3/4 brake lines from them for a 68 Body to use on my 72 truck 8 3/4. I looked at where the hose/tee block bolted on for reference. those fit right.

IMHO, if you want new get the W250 set and tweek it as needed.