You can use metal line as the civvy motor did...I have a flex line in stainless steel I will send you cheap if you want it...
The best way to get the line out and in while the motor is in the truck is to:
Take off the sending unit end of the hose.
Put something on top of the valve cover to make it tolerable to lay on for a while.
Get something you can stand on while laying over the valve cover...comfort is important here...you need your eyes to be able to see just behind the head and you need to be comfortable enough to be in this position and think well for a while...
Grab the sending unit end of the hose from the lower passenger side and lift it up so that it is straight up in the engine compartment with the unhooked end to the sky.
(Basically, you are using the hose as a handle or wrench to remove the right angle fitting from the back of the head.)
Keep moving the hose in the clockwise direction as viewed from the front until the fitting comes loose.
So...to put it in, put some thread tape on the right angle fitting for the head, put the new hose on that right angle elbow.
Laying on top of the motor, hold the elbow to the hole in the back of the head...it can be done...just so it is touching it...have the new hose sticking out low on the drivers side.
While holding theelbow in the hole, with the left hand as far to the passenger side as possible, lift the hose with the right hand, thus turning the elbow and, hopefully, starting the threads. you may have to do this several times to get it right...I have done it for 2 hoses...its not too hard with patience.
Once it starts to thread, keep rotating it around til its tight and take the hose down to the sending unit tee and connect.
NOTE: I have only done this with flexible hoses...I am not sure that a solid line could make the circle required without bending...maybe someone who has the solid line conversion can say...
Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.
Pro-choice, that's a LIE, babies don't choose to die!!