aeroquip and fragola have what you want , or send it to mark

Think I found it....

Fragola Performance Systems Flare Caps 492928-BL

Yup, good find.

I'm off the hook

Get a local hose company make you some nice high pressure lines.

Totally different situation than running fuel to your helm. I was given 2 mechanical fuel gauges 10 yrs, just never had the balls to run fuel to my helm after having a poly water pressure line leak. They are still on the shelf.

Not how you make hydrogen fuel. :) yeh, joking,

Run an isolator for a mechanical gage so fuel isn't plumbed under the dash/helm.
Leaking boost pressure or water isn't as dangerous or flamable as fuel is.

https://www.summitracing.com/parts/atm-5282/overview/

https://www.autometer.com/high-press...r-300-psi.html

Instructions

This isolator is installed in the pressure line between the carb or fuel pump (where you normally pick up fuel pressure) and the fuel pressure gauge. It has a diaphragm that prevents fuel from reaching the gauge (inside the driver's compartment). The driver's side of the isolator and the line to the gauge are filled with a fluid that transfers the pressure to the gauge.